Early Game: Stay far, use skills to harass and pick up last hits.

E is a great healing skill and does a good amount of damage. Having 2 good harassing skills makes Yorick an awesome lane champion. If the enemy champions play slightly aggressive and don't ret;reat at low HPs, it can be pretty easy to pick up the kill (Ghoul kills are always awesome!).

Mid game: 1v1 should be easy wins.

By now you can dish out a good amount of damage. Having a constant barrage of skills gives an amazing magic and regular damage. Thornmails should not pose a problem. HP tanks may be a little tricky, but you should be able to kill them before they kill you.

Late game: 6v5 team fights

Use your ultimate asap and turn a 5v5 into a 6v5. The best of this non tanky build is that you don't need to rely on an AD carry champion to copy. You can just copy yourself. Of course having a ranged DPS champion to copy could be better. Constant ghouls are also very annoying to the other team. Unfortunately, if you are focused on, you will probably drop fast, but with the life leech from both the bloodthurster and the ghoul (of famine) you should have decent survivability.

Warn your teammates about your ultimate so they don't waste it if they are brought back.

Yorick and his minions do an amazing job farming. Use Q, W, and E asap and just watch all the minions fall to waste.

Heal is a must have for this build. The fights may get intense and close. A simple heal will give a huge advantage during a fight. Team fights also greatly benefit.

I usually go with teleport as my other spell so that no time is wasted to buy items. This way Yorick will be the highest possible level.

It is a very simple and effective build. Give it a try!