Warwick is one of my go to champions and has been for many seasons,since season 1, this shall be my 8th season.
This is a movement speed/hunting build, you will be able to run anyone down including a Hecarim, which is what you want if you're looking into this specific Warwick guide.
I found it very hard to lose a game with this specific build while I was playing it myself and so I've decided to make a guide for it. (Usually the only way to lose with this is if you missplay and die or the enemy team manages to get fed off of your newb teammates)

I currently main Warwick and plan to start streaming sometime later this season. I also plan to hit at least Diamond rank for this season as i intend to take League more seriously as ever before. And this is me making sure that I reach my goals this season, this is my experience with Warwick (this is my normal duelist build however, this guide is for both the Predator build which is more fun than hardcore and the duelist build which is for ladder climbing;I'm using the same ability maxing order and item setup for both builds as these seem the most effective choices) My current Warwick winrate is over 85% and I plan to keep it over 70% for the entire season.

Start with Blue buff full clear that side then rush to Red buff and lastly Raptors. Get the Rift Scuttler and gank Mid Lane if the opportunity presents itself.

Alternate start #1: Start with Red buff and clear Raptor camp, skip small golems and go for Blue buff directly into Gromp and Wolves , then back and buy.

Alternate start #2: Start with Blue buff then invade enemy Red Buff (Note: DO NOT smite your blue buff as it's needed for the enemy red buff steal). This works against targets that need an early blue buff such as an Amumu, a Diana or maybe even a Vi or a Graves. Even some Lee Sin players (I do this aswell)will be starting with their Blue buff so that they may steal your Red buff. This start allows you to still have both buffs and keep up in gold and experience. The second you smite enemy Red buff , pop the red plant in the enemy jungle for a quick escape into the Baron Pit and kill the Scuttler in the river. After Scuttler clear your own jungle and look for a gank bot lane since you would be on the bottom side of the map by the time you finish clearing the jungle. You can also look for a Dragon clear if the enemy bottom lane has recalled when you finish clearing. Or back and spend your hard earned gold you smart farmer...
I'd say this is the more complex opening you'd do on any jungler.It's more aggressive/farm focused than gank focused so you'll be farming a lot and ganking somewhere between levels 6-8.
Note: Warwick can easily solo Dragons and Rift Heralds but it's safer to not try and be sneaky so keep your bot lane close when you try for it if you have no vision of the enemy jungler and mid laner.

Duelist Alternate start: Start with Blue or Red buff, if you start with Red buff clear Wolves before Blue then rush to clear the Scuttle Crab. First thing you want to do after having cleared the Scuttle Crab is to see if you have any gank opportunities. If you don't have any gank opportunities(or even if you do you migh want to prioritize this in some cases) but know where the enemy mid laner and the jungler is based off of where he starts in the jungle you should be clearing Dragon at this point, you should be level 3 when you start doing the Dragon and have 2 procs of Refillable Potion with Smite up and a trinket Ward behind the Dragon pit just in case. Ask your bottom and mid to pressure their lanes so they force the enemy laners to protect their turrets and not collapse onto us while we make a risky play to help our team. By level 6 we can easily clear the Rift Herald without fearing the enemy jungler in a 1v1 situation. Long press Q to dodge the herald's attacks and go behind him to hit the vulnerable spot in the back every time, this gives us a safe and easy Herald clear; but this is optional as it involves not having other high priorities.

This is a map showing you exactly what you should be doing and in what order with the red->dragon clear at level 3 start, the red DOT is where the ward goes.

One of the most important parts in this setup lies here in the ganking section.

Look for gank opportunities, even more with this build than with the others. This build enables you to gank from places no one would expect, for example: Ally Renekton vs Enemy Nasus >Top Lane; You finish clearing your jungle and are now on the bottom side of the map; Nasus ends up with 50% HP and decides to stay in lane. You decide to do Rift Scuttler and notice enemy Nasus being under the 25% HP mark, this enables you to rush from the bottom side of the map to top lane and secure a fast kill without anyone expecting anything due to the extreme movement speed this build provides.

Always look for flanks, even if you have to circle around the entire top side of the map for it to happen , remember you have a lot of movement speed so you can make things like this happen. Flanking is the most important thing in this entire Guide. It doesn't have to be early game or late game , you can flank at any moment as soon as you get your boots to activate the Predator rune.

Note:Do not always look for extremely high range ultimates because those might not happen and you might just miss a double-triple kill opportunity. Go for the safer high speed chases which are being enabled by the movement speed you get by using this guide.

Now this is the build you want for hardcore ladder climbing as this is the best Warwick build available right now. If you're a good Warwick player and know what you're doing with this , you'll climb high. I intend to use this build to reach my goals and hit Diamond+ this season as I've started to play more seriously so I can start streaming and teach people how to play better. As you've seen in the Introduction section , it's going pretty well.

Our first path is Precision , there are a couple of reasons as to why I chose this specific rune path.
First , it gives you an extremely good 9% attack speed and +6 Attack Damage which is needed for this build.

Second, we have thePress the attack rune which boosts our damage and is crucial for us to be able to outduel everyone.This rune works with your Q as you need 3 basic attacks to proc it and your Q applies on-hit effects. Basically you do this AA+Q+AA , this is our combo to easily proc our rune and amplify the damage our targets takes from your entire team for 6 seconds.

Our second rune is Triumph because of the 12% hp we get after any takedown and the extra 25gold is welcomed, this is the better choice out of the 3 we got,Overheal is the other useful rune but it can be shut down easily.

For our third slot we have the option of choosing between LEGEND:Alacrity and LEGEND:Tenacity, take Legend: Alacrity as the added attack speed since recent Precision changes is flat out better than the tenacity for your early game.
The last choice is the Coup de Grace rune which is the best out of the 3 for a Warwick, we will be dealing bonus damage to targets with low health and kills gives us a small amount of temporary AD to help us out with our damage further in a fight.

For our second path we have Sorcery with Celerity and Waterwalking. These shall be explained in more detail in the Predator path.

Domination withPredator and Sorcery are the go to must have for this to succeed.
On the first row of the Domination Path we get Sudden Impact which is the best choice since we'll be doing a lot of jumping with our high range Infinite Duress(R) leap.
Eyeball Collection is just a solid choice in general so we'll be sticking with this one.
And the last one for our Domination Path runes shall be Relentless Hunter, the added movement speed on champion takedowns is crucial for this build.

Next we have the Sorcery Path which gives us a solid +11 attack damage since we'll be going primarily AD.
Note that we want as much movement speed as possible but also damage.
So for the first rune we have Celerity which gives us nice little attack damage boost for our boosted movement speed and an extra 3% movement speed on top of that.
And for the last slot we have Water Walking, this is another crucial rune in our build since we'll be wanting to get those Rift Scuttles and spend time running through the river to gank, and also control Baron and Dragons.
Note: You may also jump from the river with your ultimate which gets extra bonus AD from Scuttle movement speed pond , water walking, celerity relentless hunter and the predator keystone rune;add boots on top of that and all the extra movement speed items + your W which grants movement speed aswell.

I'm not going to write a lot here since everything shall be explained in notes but there are a couple of things that need to be said.
For the duelist build of Warwick you generally want exactly the same items as for the predator setup.
TIAMAT this item is a must buy first back. The second item you want with this build are the Boots, yes that's right , you want Boots of Speed second.
Even though this is a high speed build for chasing targets , you want Tiamat as your first buy item for damage and fast jungle clear. The boot upgrade is not needed until mid-game.
For our Unstoppable Duelist build we're not going to get the Rejuvenation Bead as it delays our first Dragon, instead we're going to be taking a Refillable Potion as this has more life sustain than the Reju' Bead and gives us an easier time taking that juicy Dragon at level 3.
We still rush the Tiamat right after. This is still our first BIG buy.
Note: Do not waste your potion procs as both procs are needed for our first Dragon. You can do it with only 1 but it's risky and you might die to a random Pokemon trying to find a Scuttle in the river.

Eternal Hunger(Passive): You deal 10+ bonus magic damage on hit which also apply to your ultimate, and you heal on hit. This healing gets tripled while you are below 25%HP.
Jaws of the beast(Q): You want to max this second because the damage and self-sustain it gives is enough for your early game to be impactful. Also you can follow your targets by holding down the ability cast button which is set to Q by default.
Note: This follows Ezreal's Arcane Shift, and Flash as well so you can literally follow anyone through a wall even.
Blood Hunt(W): This is the ability we'll be focusing on in this guide. While an enemy champion is under 50% , Primal Howl gives you 35%-55% and 50%-110% bonus attack speed(increases per ability rank) and these bonuses are tripled while your targets are below 25%HP.
Primal Howl[E]: We're maxing this last because the base damage reduction doesn't get increased by much and what we have with our first point in the ability is enough to last us for a long time , especially since we're going for a bit of a tank build.
Grab a point in your Infinite Duress(R) whenever available.

This ability maxing order stays the same for both Warwick builds present in this Guide.

Note:Blood Hunt(W) can and should also be used to scout out for the closest enemies if you don't have vision while doing dragon as it will show you their location and it could save your life.

We're a team player but we also have the greatest kill potential in a 1v1 scenario. There is no other champion that can duel us and live to tell the story.
This build has been tested in 1v1 scenarios against champions like Udyr, Olaf,Sejuani,Renekton,Master Yi,Katarina,Jax,Skarner,Vayne,Draven,Jarvan,Garen,Darius. This has also been tested against 5man CC team compositions such as a team with Jarvan,Sejuani,Orianna,Varus and Leona and proven to be extremely effective; it has allowed us to secure multiple victories over such compositions.
Not only do we have massive tank stats but we also have massive damage as a Press the Attack Warwick.
Note: Remember that at the end of the day we're A TEAM PLAYER so we want to be helping our team as much as possible in those big teamfights.

This build does not change the fact that Warwick is one badass wolf who can 1v1 almost any champion within the Rift.
You will be having trouble fighting a full build Vayne/Master Yi however, a mid-game Renekton and probably a Garen,Darius or an Olaf oh and a good Jax might also pose a threat.
The other champions are going to run and cower from the raging speedster that you are, the only thing left is to hunt them down.

As a raging speedster , Warwick wants to Flank in teamfights, that's right. You're also a tank so make sure you also tank for your team, here's the tricky part, how do you tank without being there so you can flank the enemy team? Well, you can't be flanking non stop so you have to be with your team some of the time... also you're going to be baiting the enemy team a lot, taunting them with your super speed and pulling them towards your team, this is where your items as a tank come in so you can survive while pulling the enemies closer so you can run around into the shadows and flank them while they think you've ran off. Always look for the tanks or the carries , this mostly depends on what build you have, but always and I mean always ult one of the bigger carries in the game in a teamfight.

Duelist teamfights
Our main objectives is locking down the enemy carries while in a full on fight we can CC everyone using our(E)Primal Howl and also gives ourselves a boost to damage reduction while we position in the middle of the enemy team, this allows us to have a perfect position an CC the entire enemy team while our team does the rest of the job. Escaping low health targets will be chased down and dealt with after, unless they're high priority targets like a fed AP mage or a fed ADC.

This section is for updates to the Guide as the new runes are still new and need more testing on the duration of the season,also Riot tends to switch things up from time to time and things might change.

Update 1 (10/02/2018)
- Statikk Shiv and Infinity's Edge have been removed from the full build as they don't add what we want to achieve with this build , they've been replaced by Trinity Force and Youmuu's Ghostblade as they are the ideal items for our last 2 open item slots
- Statikk Shive added as a situational item
- Added Trinity Force as a Core Item as it is required for a huge power spike due to how Warwick's kit interacts with the Trinity Force's passive damage proc and stats , and also due to Trinity Force being just a 10/10 great item for Warwick in general
Update 2 (15/02/2018)
- Big Guide Update, added ladder climbing rune paths
Update 3 (3/3/2018)
- Updated for patch 8.4 - Dragon can still be done at level 3 easily and without fear
- Warwick's still as strong as ever, nothing feels like it got nerfed, he feels stronger actually due to the extra +6 added attack damage to the Precision+Sorcery paths
- Item list for Duelist build updated for patch 8.4 (basically the same thing only trinity force is not a priority item anymore)
Update 4 (3/7/2018)
- Patch 8.5 - Press the Attack has been buffed up again - Warwick's back and stronger than ever, feel free to maw down your foes while you climb the ladder brackets (just wanted to let everyone now)
Update 5 (3/04/2018) Patch 8.6 (forgot to change things here as I've been more focused on Kai'Sa recently)
- Changed Legend: Alacrity with Legend: Tenacity as it's flat out better due to the changes to the Precision path.
- Warwick is steal one mean wolf , mean enough to still be on top of the food chain in League as one of the biggest , strongest and meanest junglers, The King of the jungle still.
Update 6 (4/4/2018) Patch 8.7 - nothing has changed , Warwick received a bug fix that might've helped him I guess? never noticed the bug myself though so I can't say for sure but I don't think it's going to affect Warwick whatsoever
- Still the king of the jungle
Update 7 (6/7/2018) Patch 8.13 - Just wanted to let everyone know that this build is still viable and has 2 of the very best Warwick builds overall.
- Guinsoo's Rageblade added to duelist build as I've forgotten to do so in the past; recent guinsoo nerfs don't affect us much at all so it is still a viable option in some cases
- Black Cleaver added to duelist build due to synergy with Warwick's ultimate ability
- Recent Celerity changes don't affect us much in terms of movement speed but it does increase our damage by quite a lot
- Dragon at level 3 is still viable and can easily be done