Pros:
-Fast and reliable jungler
-Lots of health and dps
-Able to lifesteal all day with blue buff
-Great ganker or support stun
-Ultimate is extremely long range
-Catching an enemy is easy with blood scent (Great finisher)
-Easy to focus a fed or dps champ
-He's a wolf

Cons:
-Requires team work when ganking
-Needs great map awareness
-Sometimes can get focused down (Though if they are focusing you down its fine since your kind of a tanky dps)

Smite - this is the king of warwick summoner skills. You will recognise a good warwick if he has this skill. One of the skills you will ALWAYS use. Untill late game even. Great skill for taking down big mobs fast late game or mid game to speed up pushing lanes.
But the main prio is to make your jungling effective way of getting cash and lvl faster in early mid game.
I will explain when and how to use it a bit later.
This is also the reason you have to pick Plentiful Bounty in your Mastery Tree.
Lower cd and another gold is always good.

Flash - All around great skill. Lets you land that last hit faster. Lets you run away from a gank. Lets you run away or engane an enemy to/from jungle. Lets you tower dive->kill->blink away into woods. My favorite skill.
You will just love it for cover in woods->flash out->ultimate->kill.

I use 1/16/13 for my masteries.

1. Buy Cloth armor and 5 Healing Potions and go Blue Golem
2. Next: Wolf
3. Next: Wraiths
4. Next: Lizard camp
5. Next: Golems
6. Next: Gang

Eternal Thirst: (Passive): Each of Warwick's attacks will heal him for 6 / 12 / 18 health. Each successive attack against the same target will stack this amount of healing to Warwick up to a maximum of 3 stacks per strike. The stacks remain for 4 seconds.

Hunger Strike: (Active): Strikes an enemy for the highest value between the flat magic damage and a percentage of the target's maximum health, and heals Warwick for 80% of the magic damage dealt. Monsters will only be dealt the flat magic damage.
Range: 400.

Hunters Strike: (Active): Warwick lets out a howl that inspires all allied champions, increasing Warwick's attack speed and all friendly champions' attack speed by half of the amount for 10 seconds.
Cost: 35 mana.
Radius: 1,200.

Blood Scent:(Toggle): Warwick senses enemy champions under 50% life within a certain distance of him revealing them until they heal, leave the area or Blood Scent is deactivated. While sensing an enemy, he gains extra movement speed.
Cooldown: 4 seconds

Infinite Duress:(Active): Warwick lunges at an enemy champion instantly, suppressing them for 1.7 seconds. On the time they are suppressed, Warwick strikes the target every 0.33 seconds (5 times total) for 33 % of his attack damage as physical damage plus additional damage as magic damage. During this time, he also gains 30% lifesteal. Each of his strikes proc on-hit effects and the physical portion of the attacks benefit from lifesteal.
Range: 700