Now I've been playing Warwick for awhile now. He is an amazing 1v1 fighter, but can sometimes get a bit lost in a teamfight. I writing this guide just to show a little bit how i build a Warwick. I've been known to solo baron while my team fights so that the enemy team doesn't realize it. Enjoy and please upvote!

Pros:
Strong 1v1 Champion
Solo Baron Capabilities
Has a surpress
He is a werewolf!
Cons:
Not real efficient against more than one enemy
Can be squishy if not built right

Runes are very essential with Warwick.

It's basic runes for pretty much every AD champion.

Marks are obviously Attack Damage. If you feel you want the Speed mix Attack Damage with Attack Speed.

Seals are always armor! The more armor the harder it will be for the enemy to kill you given it is while ganking or just tanking top lane.

Glyphs will be magic resist just because... well it's MR. 'Nuff said!

Your masteries will give you the essentials you need for beginning game and so on. View them at the top.

Bad news with Warwick jungle. He can be a weak jungle pre-level 6. So he is more of a farming jungle, stacking as much gold as you can through creeps to buy essential items. If you feel ballsy for a gank pre-six go ahead, but I don't recommend.

Your creeping and jungle is basically like any other jungle

Red > lvl 2 Gank/Wraithes > Wolves > Blue/Golems > Gank

or

Blue > lvl 2 Gank/Wolves > Wraithes > Red/Golems.

I favor the first one. The grabbing of Red first makes the lvl 2 gank good slowing enemies and then draining their life.

Teamwork is very essential. Without the teamwork you can useless if you are against more than one person. In a teamfight you can be very effective though:
1. Be sure your Blood Scent is active so to quickly close gaps between you and a injured champion
2. When closing in on a fight use Hunter's Call to increase your Attack Speed and your Allies attack speed to help finish the fight.
3. Remember to use Hungering Strike to easily maintain your life. Also don't forget it can have a bit of range on it over your basic attacks.
4. Never forget your Ult!! Pretty much Infinite Duress can never be wasted. If a team fight is going on in mid and turns out their Jungle Jarvan IV is fed. Run in and surpress him so either you or your allies can finish him off.

Combos

Hunters Call > Hungering Strike

or in a Team Fight

Hunters Call > Infinite Duress > Hungering Strike

With these combos it's quite easy to help significantly in a team fight