In this guide I will explain how I play Yorick. But to start things off I play Yorick as an high Attack Damage harasser who can clean up a creep wave without a problem. He can also use his ultimate as Shaco uses his hallucinate, though Shacos hallucinate is better because it has a lower cooldown and lasts longer (but it doesnt revive anyone and only deals half damge to turrets where Yoricks clone will do all the damage that you or whoever you cloned does.

I first start with the lifesteal omen because you need to stay in lane as long as possible. I then get a point in my attack boost/speeding omen and then my slowing omen. I then get my life steal ranked up (use when need health or to last hit a minion and watch the omen go right after the enemy champions). I then get my attack boost/speeding omen for the extra damage and the harassment there after. The slowing omen will damage all those in the area it was cast in and then slow enemie's around the omen (you could also get this first to check bushes but then you are stuck going back before you are ready to, I also don't recommend this because of the short range-as soon as you place it you will get focused if they are actually there-)

Sorry that I didn't show the steps on how I build into the items but I will explain the here. And all these times when you go back it will depend on how much gold you have.

First----Meki Pendant and two Mana potions
Next time you go back----Tear of the Goddess and Boots of Speed
After that----Manamune and Berserkers Greaves
Continue----Start building Phage or get it
Then----Frozen Mallet and Zeal
Then----Prioritize getting Warmog's Armor
If the game isn't over----Bloodthirster and Phantom Dancer

The reason why I don't get the Bloodthirster really early is because you already have a lifesteal ghoul and not as required as it will be late game. The Phantom Dancer is so that you can get closer to the enemy since you don't have any closing distance moves and need to get close to either use your attack boost/speeding omen or your slowing omen.

When you are in early game you need to keep harassing with your life steal or slowing omen when you see the enemy champions get a little to close. Then you need to keep putting out your other omens when they run away from your life steal or slowing omen. And soon enough you won't have to worry about mana and can keep putting out omens as soon they are able to be used, which will make have you making many minion kills.

Pros
-a pain in the butt to lane against
-omens (excpet ult) go after champions after their first target dies
-can put out damage as if he is a carry
-long time in lane

Cons
-mana hungry in the beginning
-item dependent to an extent
-not very good at chasing early and mid game