+ Strong in early/mid/late
+ Easy to play, hard to die farming jungle
+ Can fight Drake easily

- Can't play without blue buff in early game, he really needs it.
- Out of meta (there are a lot of better junglers)

Q = You can follow the target if you press it. For example, you can follow someone that uses "Flash", Tristana's "W", Lee Sin "W", Ezreal "E", etc.

W = It was a lot of cooldown, so you have to be careful.
The enemy you target will notice, so once you use your "W", start running.

E = It is pretty important to remember that your "E" reduces all incoming damages, so it is useful if you are escaping, or being about to die by a tower hit.

R = The range of your "R" will scale with your speed movement. Faster, Higher.

If you want to gank, use your "W" for the speed movement, activate "E" once you get close to an enemy, then, you press "Q", once you are behind the target, reactive your "E". That is the simplest combo.
I don't recommend using your "R" quickly, just if you think that you are not going to have range for your "Q". Warwick can do pretty good ganks without his "R", it can be more useful if the enemy manages to escape your principal combo.
If you have the chance, run behind your enemy, without using your "Q" and activate your "E". That will help you if he tries to "Flash", because you will have your "Q" as a last resource.

Warwick can always be a good option if you need a tank, but not if there are already 2 tanky champs in your team. In that case, just pick something else.

I always recommend to buy "Cinderhulk" first, and "Titanic Hydra", in that order. Unless you are to feed, buy "Titanic Hydra" first, but before buying "Spirit Visage" or "Dead man's plate", finish "Cinderhulk".

Against AD, buy "Dead man's plate" as third object.
Against AP, buy "Spirit Visage" as third object.
Always buy the "Spirit Visage", even if there are not AP enemies.

The rest is just practice...