This build is about taking the smallest amount of damage from minions and also obtaining gold early on to give you smooth sailing till level 18.

[*] Get bladed armor because it's like a small thornmail.
[*] Hardness is maxed out for extra armor to make jungling less painful.

[*] Weapon Expertise and Sunder are a must for middle and late game
[*] Vampirism simply reduces the need to buy health potions at the start like most builds want you to.
[*] Max out Sorcery and Arcane Knowledge instead of Deadliness and Lethality because Deadliness does not really help you at all early game and you need that extra 10% magic penetration to help your Hungering Strike dish out more damage and restoration.

[*]
[*] DONT GET HAVOC! its not worth it, especially early in the game when ur jungling or ganking. Say you get a total damage output of 50,000 in one game, if you only put 2 points into Havoc, you get 1% damage dealt...meaning you gained a whole 500 damage that game....which means you obtain 0 change in your damage output while jungling.

[*] The last item is left out because it all depends on what else you need to be unstoppable
[*] Frozen Mallet to keep them from escaping even more and giving you more health incase you find yourself dying more than normal.
[*] Thornmail if you're dying mostly from basic attacks
[*] Last Whisper if you can't seem to do much damage to tanks even with Bloodrazor
[*] Cloat and Dagger must not be left out especially if the other team likes to CC (crowd control), some tenacity can go a long way. (dont stack with Mercury's Threads)
[*] Malady is a good choice if you're not content with how many dots your able to do.

[*] I dont worry very much about health potions cause you dont really need them, I usually grab 1 just in case and start working on boots so you can gank without them having a chance to run away.
[*] Bloodrazor and Black Cleaver stack with Warwick's ult (as it will tell you in the tips layout in LoL) so you want to make a point to get those items and other items that will increase your dps (damage per second) by giving you many dots (damage over time) and also lots of attack speed so you can deal out those dots as fast as possible.

[*] Start your gank at level 4 after you get your second Bloodlust just keep an eye on weak enemys to attack, or weak teammates to give assistance. IF YOU LET YOUR TEAMMATES DIE, YOU WILL LOSE.
[*] If it looks like everyone is at full health and doesn't require aid, then keep jungling till around level 7 or 8 by this time you should have enough assists and/or kills to be able to get yourself boots and Bloodrazor, or at least close to Bloodrazor.

Pros: Cons:
[*] Easy jungling [*] Rather squishy
[*] Really good damage mid game [*] Hard to recover from early game fails
[*] Able to take down tanks fairly easily [*] Very team dependent
[*] Good survivability due to passive health regen

The reason why I recommend getting Bloodscent 3rd and 4th is to be able to gank when you reach level 4 and before any of the other enemy team has a chance to upgrade their main ability to level 2, you have the advantage regardless of what abilities they decide to max out first because chances are they decided to level up all their abilities to level 1 before upgrading anything to level 2