Well this is the way I like to play my Warwick. I like full on speed and life steal. its successful. It is easy as long as you build it right and it is actually not that hard to play. But what i like to do is sit at the bottom and help my team mates accomplish what is need and at first you wont be strong but once you reach level six and have acquired the lantern and boots you should be able to gank like crazy. Go easy on me though this is my first build lol but it has been successful for me and I will post some screenshots of kills and deaths

This is just what i would prefer but anything you like will work but this is my personal preference.

I would start with hungering strike or hunters call. either way as long as you build those two the most you will be fine. i usually start with hunters call for that speed but if you have strong people on your team then just go with the strike to get easy kills with a powerful attack

The items use them as follow always get the sword, razors, then lantern though. Also bilgewater cutlass and executioners calling are optional for the bloodthirster. If you want to experiment with anything i would just look around the attack speed section and the life steal though because that's what this build is really meant for.