THIS IS A SUMMARY OF THE NEXT CHAPTERS. IN DEPTH IN NEXT CHAPTERS
So Start. Hunters machete and BEADS, - Tiamat 1st back, - Stalkers blade warriorWarrior - BOTRK - Beserker GreavesBESERKER GREAVES (these 2 do not matter order if you can get boots do) - Ravenous hydra (This is when trundles life steal becomes god-like) - Then Deaths dance and Triforce
Start red then raptors 9If you want a more in-depth will write it later) then whole blue, MAKE SURE WHEN 1v1 CHAMPS YOU USE 'W' THEN Q OTHERWISE YOU DONT HEAL OR DO AS MUCH DAMAGE
W is so stronk
also you level up in order of
Q -W -E
When ulting in team fights do it on the tank
Always use ULT in 1v1 its super strong ESPICALLY IF YOU ARE ON THE 'W'
Ok Your pillar changes EVERYTHING, do not use ( well you can but sometimes its really not needed ) to engage, use it once they begin to run away and are not in SMACK range, this gives you the advantage to chase down. Also once you become a God tier trundle, you can predict flashes and spell movements to knock them up and counter them, ALSO its busted as you can sometimes wedge people in walls by placing it close enough the wall that there is a sliver of space between and the enemy champion cannot walk through but if they click away makes them try to walk through
And remember to smack
How to play trundle :D

Start Red buff, with a good leash you should be able to only use Q twice. Head over to Raptors (This is when it begins to get slightly technical). Use your 'W' and you can auto attack cancel the animation of the 'W' and attack the baby raptors, Use your 'Q' once 'W' runs out you should only have 2 baby raptors left. Pummel them then 'Q' the big raptor once. heading over to blue side you should have around 60-70%hp and 50-60%Mana.
Blue side.
Head to wolves and use 'W' once and pummel the small wolves then 'Q' the big one once, this seems to be the quickest route I could find. Then 'W' 'Q' Blue buff and continue over to our big boi Gromp With the mana regen 'W' then 'Q' as much as you need to. You will need to use a smite here on Gromp. Head over to Scuttle Crab. That is your jungle start sorted! Next chapter is further farming.
So in your fist clear summed up you take everything apart from Krugs. You don't really touch them until you get your Tiamat. You can take them if you have smite but sometimes isn't worth when you can go in for a gank.

Personally I play trundle as a bit of a power farming champion. He is incredible at ganking but his farming can be very good.
Getting a good cycle on your farm is important usually I can get 1 full cycle (Then try to set up for a gank), then continue to circle round and do another full cycle (without buffs as they wont have respawned) but after this look for a gank either top or bot lane (The respective side which you should have finished at) After completing this your red side should be resetting as you are walking back to the jungle. respectively Drake should be up now so coordinating a gank and push botlane after completing your redside to then take drake is a strong desicion rotate to your blue side and take control of that. (This is of course if you are on the southside of the map.

Coordination is key, remember that.
Crowd Control (CC) is your best friend with Trundle, as you do not have a root or a stun it is hard to solo gank. Talk to your Lanes to get a successful gank off. If you can coordinate a CC push in with that. use your 'W' to advance in quickly. Upon this try to 'Q' This slows your enemy, If they have flash or an escape move the enemy may use this now (Such as dash etc). This is when you use your 'E' so you can catch them up unexpectedly as they are knocked up momenterally and you and your laner can catch up to them and smack them.
Easy simple gank guide, any questions please ask :)

This isn't going to be too long of an explanation. Its pretty simple.
Before using 'Q' make sure you use your 'W' This makes it do extra damage and Life steal. Do not use your 'E' until you need to disengage or catch them up so you can kill them. Trundle is incredible in 1v1. Especially against tanks after level 6. If you think you may not 100% win the 1v1 without your 'R' . Just use it. Its cool down isn't too long and it can nearly always guarantee you the win the fight. Trundle is surprisingly good against assassins in 1v1 as he can retain the life steal, (this may not be the case late game if the opposing assassin is fed. but by then you should be too) Trundle hits hard so be heavy in counter jungling ward well and you should smack the enemy jungler.

So, this changes everything.
Your pillar can change every possible fight. Here goes.
As I said earlier use it to engage or disengage EARLY game. This is strong for ganking as I explained earlier. But, if they are running away there is a glitch, If you use 'E' near a wall in the jungle, do it so there is a big enough gap which can physically see but not enough for them to be physically able to walk through. If the enemy are dumb they will click on the tower and auto walk away. this is a downfall upon playing against trundle as it can make them walk into the small gap which you can pin them in. Also you can trap people flashing away in that small area as they go to Flash you can pop down the Pillar meaning that there flash doesn't actually reach over the wall and they flash short waste flash and do not escape and die. Big win.
Finally, late game Team fights. Pillar can cancel channel 'R's and other things, for example Miss Fortune's You can pop your pillar under her and cancel it denying a team kill for the enemy team. (Same with other channeling Kill moves.)