The picture explains it all... Yorick is one of those champions that can take down teams 1v5 (if played right) and push harder than a pregnant Sivir. In this guide, I will be discussing my strategies I use while playing him casually and in ranked play. His main role (at least in this guide) is to be the TANKY AD CARRY. Note: Tanky AD carry and Tank Yorick have some minor differences which I will discuss later on. If you're not here to learn to do MASSIVE damage and not die, then you're in the wrong place.

Pros
Strong throughout the game
TANKY (with my guide he reaches 4000HP)
Does sh*tloads of DAMAGE (with my guide it can reach to 400 damage)
Tons of utility
Most importantly, HE CAN HEAL HIMSELF

Cons
Needs good farm and last hitting (it isn't too hard getting all his items before 40 minutes)
Kiting Yorick is possible
Falls off SLIGHTLY during mid game
LACKS MP early game
Needs good timing for Omen of Death
Something to keep in mind, hes a MELEE CHARACTER

Note: These Pros/Cons account for only my guide. As for every champion, Pros/Cons vary depending which skills, masteries, runes, summoner spells and items you take. Having this said, keep in mind that these Pros/Cons applies mostly to my guide and that it is what you can expect following my guide.

As for runes, you basically have a general direction for each one.

Marks
Marks can be anything that contributes to his damage output. I will also talk about its contributions to as well as later on in the guide.
Greater Mark of Attack Damage - RECOMMENDED Using these helps your early game a tremendous amount more than other marks. However, it doesn't become as great late game as the other Marks. Even though, early game is the most crucial part of the game which determines if you will carry your team and this is why I'd pick this Mark over all the others.
Greater Mark of Scaling Attack Damage - Gives you a better late game for those games that go on after you reach Level 18. It gives more than 2x the effects of Greater Mark of Attack Damage once you reach 18. However, what you game for late game you will lack for in early game.
Greater Mark of Desolation - These help throughout the game with your damage however will lack some early game.

Seals
His seals can go 2 directions. Either if can additionally support his damage output, or be used to better his defense.
Greater Seal of Attack Speed - RECOMMENDED Like I said in the Pros, he will end up reaching about 300-400 damage late game. With this said, having the extra attack speed will help you in both last hitting early game and dealing damage late game.
Greater Seal of Replenishment - This really helps with your MP problem early game if you tend to run out of MP quickly. However, after you build up your Tear of the Goddess and later on Manamune, it will begin to lack in importance. If you chose cooldown Glyphs and you need more MP, this Seal would be a decent substitute.
Greater Seal of Armor, Greater Seal of Magic Resist, Greater Seal of Health - These seals help you with your survivability and aids in lasting longer in lane. If you want to last longer in lanes or be able to tank for your team for a little longer, these seals will help you achieve that. As for which one to use, it really depends on which one you prefer.

Glyphs
There isn't much direction in Glyphs because there are obvious choices of which Glyphs to pick for Yorick.
Greater Glyph of Cooldown Reduction - RECOMMENDED Having all 9 Glyphs will give you almost 6% cooldown reduction and with Ionion Boots of Lucidity, you will have around 21% cooldown reduction not including blue buff/elixir. Cooldown is a major part of Yorick's gameplay and these runes would aid him push lanes and farm faster.
Greater Glyph of Replenishment - Same explanation as Greater Seal of Replenishment

Quintessences
It doesn't really matter which Quintessences you pick, it's mostly your preference. I would however recommend adding more in either armor pen, flat AD, cooldown reduction or attack speed.