Build is focused on MS and sticking to the target, HP items with some sort of MS and AD are a good match for Briar and will be further discussed in the next chapter.

Stridebreaker gives MS and slows enemy down which is perfect for Briar.
BoRK is a bit greedy since it provides no tankiness but the item is good for AA'ing and sticking to the target, also good stats.
Wit's End gives good MR but no protection against Physiscal damage, it also gives AS and MS.
Black Cleaver is good, gives AD, MS and HP. Briar likes it.
Steraks gives AD and provides tankiness to a champion that needs to survive do deal damage.

Not much to say here pretty starightforward champion, you chase people and try to stick to them, the main concern is if the area around is safe since you gotta know when to cancle your self-taunt, if you are near an enemy tower you should be carefull and preserve you E, maybe keep a ward or 2 to help the pathfinding when fighting near bushes.
Don't try to defend from a lvl 1 invade positioning is gonna kill you.
After level 3 disable any kind of self-preservation mechanism you might have and su***b to your primal desires of chasing everything, think that everyone has Warwick's W passive and go, chasing on briar is good, avoid beeing chased but in case you are just use E wiselly and if you are feeling lucky R yourself into a less difficult situatiuon, could also consider a hunter becomes the hunted situation tho Briar's W recast is very powerfull.
Ultimate doesn't have that big of a cooldown and can be used often, it's more fun if you try to do it from far away and please do not aim it close to turrets and most importantlly, fountain.

Very easy and fast jungle clear, W has a tiamat and gives health, E also gives you health and deals a lot of damage, passive is very strong as welll.
Drakes can be done alone and you finish them full HP if you use the W well, obviously better with teamates but I'm bronze I wouldn't know.
Herald is also easy and W can be used in between the eye opening timer with no issue.
Baron is also easy to do.

I was attempting to hit the Full Guide milestone but was missing a couple of characters so I decided to write this, there will probably be a lot of typos but I'll probably be the only one to read this anyways, if you're a random Mobafire user that went to deep, hi.
I still need to add a couple of characters but I have no intention off improving on the quality of this guide so I'll just give you a recipe for chocolate cake given by Chat-GPT:
In a bowl, mix 1.5 cups flour, 1.5 cups sugar, 3/4 cup cocoa, 1.5 tsp baking powder, 1.5 tsp baking soda, 1 tsp salt. Add 2 eggs, 1 cup milk, 1/2 cup oil, 2 tsp vanilla. Combine well, pour into pans, and bake at 350°F for 30-35 mins. Let it cool, then savor your delicious chocolate cake!