This is my first draft of my first guide, so I'll keep it simple.
I am focusing my build on AD, health and cooldown reduction.
"Why AD and HP?"
Because Yorick's Ghouls have bonus based on his AD and HP. Simple, huh!?
"How about cooldown?"
If you have a huge cooldown reduction (this here is not huge), you can spam your skills giving more damage and healing more with your Omen of Famine

I start with the Sapphire Crystal just to have more mana to keep me more time in the lane. I also buy 2 Health Potion for the same reason.
Following I like to buy the Tear of the Goddess to increase my mana and the Boots.
Then rush the Manamune, 'cause I'll get more AD.
I have chosen the Ionian Boots of Lucidity just for the cooldown reduction.
Phage will give us the 2 things we are looking for: AD and HP. Also The slow is always useful.
B. F. Sword - more AD and preparing to Bloodthirster.
Well, I think I don't need to explain the Warmog's Armor.
And the Youmuu's Ghostblade besides the AD, its Passive and Active bonuses are pretty nice as well!

So, one important thing on my build is the mana. The Manamune will make my mana grow and therefore my AD. So after I buy my Tear of the Goddess I am always spamming the Omen of Pestilence wherever I am (this is the only skill with I can spam alone, without an enemy around), but, of course, I rather spam my skill over enemy targets.

I think I have made myself clear about wanting AD, HP and Cooldown reduction.

I like to start with the Omen of Famine due to its life regeneration. However, it might be good as well start with the Omen of Pestilence due to its area damage, better for creeping and make some money.