Hi there, so I've been playing Yorick since he came out, and after countless (not countless but the number is embarrassing) failures, I finally figured out how to make Yorick the best character in the game. Just follow this advice and you'll be destroying with him too.

Pros
You smell bad, so maybe the enemy will gag, throw up and die for you

Cons
You're ugly
You smell bad (both pro and con)
You do no damage
Your dance sucks
You do no damage
You're armor and magic resists are terrible
You do no damage
You're squishier than a teemo at lvl 1
You do no damage
You have very limited range on your skills
You do no damage
And finally, you do no damage

There are only 2 words needed to describe how to play with Yorick....

You don't.

I pick the Avarice Quintessences because without them, Yorick can't get enough champion kills, assists or cs in order to get enough gold to even buy a health pot, let alone anything even remotely useful.

I picked Deadliness and Archmage's Savy because Yorick needs to do both kinds of damage, AP and AD, otherwise he only does half a damage per hit, instead of 1.

You need improved of every summoner spell you can, because without all of those improved summoner spells, Yorick can't do anything. He needs them to be useful.

Also, Yorick needs Expanded Mind, because without it, he's stupider than a dragoon from Starcraft Brood War. For all of you non-starcraft players, that means if you tell him to go to mid from the base, he'll go top then run down the river to get there.

Yorick's ulti is his only useful skill, so just focus on that for the whole game.

Yorick needs the 65 tiamats, because without AT LEAST that amount of splash damage, Yorick won't be able to hit for jack. He doesn't have any good aoe, so he needs the tiamats badly.

I chose Revive because, Yorick is going to die a lot, it's just going to happen, so revive is necessary for making sure you can participate in team fights and to insure that legendary kill for the enemy Xin Zhao.

Promote is require! Never play Yorick without promote. He needs to promote all of his ghouls so they might actually do some damage...maybe...possibly....probably not.

The top 3 mistakes when playing Yorick are as follows:

1.) You played him
2.) You bought him with IP
and the biggest...
3.) You bought him with RP

Don't go mid... you'll feed.
Don't go top... you'll feed.
Don't go bot... you'll feed.
Don't jungle... you'll feed.
Don't roam... you'll feed.
Don't counter jungle... you'll feed.
Don't just sit in base, because if they have an Ashe, a Karthus or an Ezreal... you'll feed.
The best thing to do at this point is just act as a meat shield for your team, die, revive and then do it again.

Well, that about wraps up my Yorick build. Just remember the 2 key words on how to play him and you'll be guaranteed to never fail with him.... just don't.