This guide is simply what I have had success using, I by no means claim for it to be the best, I just wanted to share what has worked for me, and any constructive comments are encouraged.

Flat Attack Damage reds, I use these because Yorick's ghouls damage scale off of Yorick's Damage

Flat Armor Yellows, I am sure there is a better choice for this slot, but I have had success using these, and I am poor and only have two sets of yellow runes.

MR/Level Blues, seeing as I don't really get any real defensive items, it doesnt hurt to put some magic resist in, as with the yellows, I don't have access to a lot of runes as of yet, and they seem to work for me.

Flat HP quints, they scale with the ghouls as well, and it definitely help having the extra HP early game.

The masteries are 21/0/9
I Like to go 21 into offense because obviously the increased damage, but I feel as compared to the other trees it offers a lot more in terms of the useful placement of points. there are no wasted points in the offensive tree. The 9 in the Utility tree are for the increased regen and the EXP gains.

I Start off with a Doran's blade, the Health and Damage scale with the minions, and the Life steal while small makes a difference.

When I first go back to buy, I like to have enough cash for level 1 boots, and a Tear of Goddess so I can start building up some mana. Depending on if I was doing ****py in lane I would buy another Doran's Blade, and if I am doing well I would buy a level 1 boots, and a Manamune.

Once Manumane is complete I get level 2 boots and start on the Triforce by purchasing Phage.
For the level two boots, as you always should I buy situationally depending on what the other teams comp looks like, sometimes I get Merc's, sometimes I get Ninja Tabi, and even Ionian would not be a bad buy here.

When the Triforce is done, that is when your real damage output comes into play, your increased damage from Manamune should be around maxed by this time, and mana problems should pretty much be eradicated. This is pretty much the core build, I Start then buying the necesarry pieces for a Blood Thirster.

If the game goes on much longer, then buy some situational items depending on the other team. A GA is not a bad choice on yorick, if you've got a lot of cash you can get a Warmog's and an Atma's and see some huge damage outputs. but really you deal quite a bit of damage at this point already.

For skill sequences I see a lot of people maxing E or W first, but I disagree with doing that, I think that Q should be maxed first, not because of how much damage it deals, but the movement speed is incredibly useful on him. In mid game when I have my TriForce and Maxed Q, you can run up to the enemy wraiths in the jungle hit them with a Q and move very quickly into mid for a gank.

Early game you don't need to use E to harass, I have read that people are saying Spam E on whoever your laning against, that is a good way to go oom fast. With Q you can use it to last hit very effectively and when the ghoul spawns it automatically will go and harass the enemy champion. also the increased movement speed makes it very easy to dodge any skill shots that the enemy may try to land against you.

After I get Q maxed I level W and E evenly, while it is not conventional to do so, I do it because maxing one gives you no Great benefits, but leveling them evenly you get the increased slowing speed on W and the decreased cooldowns on E at the same Rate.

For summoner spells I like Flash/Exhaust, Flash because it is the ever useful escape/ engaging tool, and exhaust because chasing down hero's is something that yorick excels in.

A useful combo with this is to land your W on the enemy, flash onto him and hit him with your R, followed by an E, and you have all three ghouls, a slowed enemy champion and your movement speed is increased so that he is not getting away from you.

Just a few things I have come upon while laning with him

VS teemo, when you see teemo put down a mushroom, put you W down right where he places it, teemo's get really annoyed with this one.

your W is a very useful spell for checking bushes and for checking If the enemy is doing Dragon/Baron

When playing with a Zilean, make sure you don't double ulti one person, because Yorick's will most likely be wasted. There was one time when I played with a Zilean we both were about to die, and we ulti'd each other, he came back and gave me movement speed and placed some bombs, on the enemy , and I got a triple kill while he was the only one who ended up dying. there can be some Great synergy there.

While Yorick is great at chasing down enemy champions, know when to not go too far...

When Yorick has all three minions active, he can actually be quite tanky, don't be afraid of being in the middle of the action.

Yorick is very good at farming in early game, he can lane without a problem against most champions, and he has no need to spam ghouls, at the enemy champions, at least not until you get a Manamune.

Early game farming use Q to last hit, do not be afraid of being harassed by enemy champions because more often than not, they are running away from your minion trying not to take damage from it.