Warwick is one of the best jungler in Lol ,and after lvl 6 you can gank the others :)
I hope my following Guide will help you !

Greater Mark of Desolation ( + 1,66 armor penetration )= For the damage ;)
Greater Seal of Evasion ( +0,75% dodge ) = For lucky situations
Greater Glyph of Focus ( - 0,65 % cooldowns ) = That you can spam youre hungering strike

Its a combinations i tested , and it worked well !
You can also use a 0/21/9 build or 9/21/0 but for jungeling its better to use a 21/0/9 build
The reason =
You have to skill 21 points on attack for the dmg to minions for example mana golem for the start, and with this build its easy and you can do it without any help.
The 9 points to utility becouse you need experience bonus and the utility mastery ( becouse you killing always the buff mobs )

Vampire scepter is good for the start life steal , means you can pwn the mana golem first ;)
Warwick needs attack speed , damage but also life steal , cuz its warwick , you know .
The items i choosed will give you the ultimate strengh in the late game.

In the jungle you dont need the blood scent , but you have to skill it on lvl 3 one time , becouse you maybe find a hitten enemy player in the jungle.
Hungering strike will save youre life against the first Jungle mobs at when you reached lvl 2 nothing will be a problem for you with the hunters call

You HAVE TO USE smite in the jungle for the start. You wont survive.
I took speed becouse = Its only fun if they run ;)
But you can also use flash or ignite

Pros =
good jungler
damage dealer
good in a 1v1
a fast champion
you can gank that *****es
Cons =
You will be the first ,who die in a teamfight

Start with the mana golem ->wolfs->wariths->Elder->golems->wofls->go in the enemy side to kill theire creeps but attantion ( only if the mobs on youre side respawn to slow ;) )
You can also use = Golems->wolfs->mana golem->wraiths->elder->golems->wolfs