Many people believe Yorick was, before his buffs, a very weak champion. This was never true, he was just very misunderstood. Sure, his mana could run out if he spammed his spells. So what? That happens to every mana-user if not played right.
Yorick's damage has always been very high due to his insane Q, ridiculously good passive, and his minion auto-attacks. His survivability wasn't anything to be taken lightly either, when he was built the right way.
Here are some things that I've learnt in my time playing Yorick in top-lane solo, enjoy.
The flat AD reds are self-explanatory. More damage early game = more harrass, more denying, more kills.
Yorick's mana is still a little hairy at some points in the game, mainly around mid-game if you aren't able to take Blues buffs so I use MP5/lvl yellows to counter that. I find I have very little mana issues with these once I get Philo Stone and Sheen.
Because with this build I buy Atma's quite early, I find I don't miss the Armor yellows at all.
Dual AP teams are really becoming very popular, and so Yorick is more and more likely to be facing a mage in top lane. Between flat MR blues and your passive, you will be unkillable for any mage.
Quints are really very dependant on playstyle, and personal preference. I like to take flat Health, because I aim to land my Q on the enemy laner quite often, which can easily turn into more than just harrass. Another great option is flat AD.
The 21 points in utility is untouchable. The CDR, Mana Regeneration and Movement Speed make this by far the best tree for Yorick. Having your summoners more often and some extra exp isn't too bad either!
Usually I would say to take only 1 point in Perserverence and 2 in Good Hands, but I feel the mana regen is much more important for Yorick, as his spells are still pretty expensive... plus he impossible to kill anyway.
The 9 points in defense increases his survivability, as well as his lane sustainance - exactly what we need.
Ignite - Yorick's full combo of WEQ really does a LOT of burst damage. Ignite adds a new level to this, and can get some very surprising early kills from 75% even on other Tanky DPS.
Ghost - Ghost will get you to fights faster, keep you on that slippery Vayne, or help you escape from a bad position. Flash is also viable, but I just don't find that it is as useful as Ghost is for a melee, especially in teamfights where you need to just train down the enemy carries and mages.
Flash - Though Flash is a viable spell for Yorick, I find it somewhat lacking for most bruiser-type champions. The reason being that melee with no hard CC, including Yorick, need to stay right up the *** of the people he needs to kill, and Ghost is just better at that job than Flash.
As an example, if Yorick Flashes to reach a target that he would otherwise be unable to catch, that champion can then just counter-Flash or use some escape spell. With Ghost, Yorick will sprint upto the enemy and smash their head in with his spade, force their Flash, and then run straight back upto them again because Ghost is still active.
For a level 1 fight you can start with Q or W. I usually prefer W just for the slow. If you aren't fighting at level 1, take E. I usually follow that with a rank in W for harrass, then max Q.
The choice between W and E when you can't level Q just depends on how your lane is going. If you are getting harrassed a lot, take another E, otherwise max W.
Take your ulti at 6, but only level it up after that if you have a fed/farmed AD carry on your team. If you don't, the damage increase is kinda pointless.
Maxing Q First - Explanation
I know what you're thinking: WTF WHY MAX Q IT DOES LOWER BASE DAMAGE THAN W AND E AND SCALES LESS WITH LVL OMG SCRUB.
Well you're wrong.
The base damage value of the initial Q hit (30/35/40/45/50) is indeed lower than W (60/95/130/165/200) and E (55/85/115/145/175), but many people forget the increased minion damage. The Q minion deals an additional 8/16/24/32/40 damage per hit more than the other minions.
Now, seeing as it will probably make at LEAST 2-3 autoattacks before it dies, that makes the base Q damage per lvl look something more like 54/83/112/141/170.
Now that's more in line with the W and E values. However, the cooldown on Q is considerably lower than both other spells, meaning that it deals much more damage than them both over 10 seconds or longer.
Starting with Regrowth Pendant gives Yorick even more health regeneration, which is perfect for his laning phase (as his harrass is currently OP). With this I take a Mana Potion as his mana early game is still quite bad if you spam your spells, and you don't need any health potions because of his E.
Another option is to start with Boots of Speed and 3 Mana Potions. If you know you are going to be laning against a ranged carry or mage, you may want to take boots at lvl 1 so you can get some easy early kills by landing your Q more often. Again, I find mana potions a necessity on Yorick, and being able to take 3 allows you to harrass enemies more than they will be able to deal with.
After my first port I aim to have at least Philo Stone and Boots of Speed, maybe with parts of Heart of Gold or Sheen if you got a kill or had time to farm enough.
The main point of the Philo Stone (other than the gold per 10) is to keep you laning, farming, and harrassing longer. You will eventually sell it if the game doesn't end before you need the item slot.
An early Sheen is really great for the burst it can land, as well as giving Yorick some more much-needed mana. You can get this before or after HoG, depending on how many melee hits you are getting on your lane partner.
HoG is another great source of health for your Atma's, as it builds into something you may want later, Randuin's Omen, and also of course generates more gold.
Atma's Impaler is essential for this build to work. It lets you build Yorick really tanky while still doing a lot of damage. As soon as you get this, you can start building more health starting with Giant's Belt, and start fighting 1v3 (really, you can).
Next, rush your Warmog's Armor. You want to do this so you can start stacking it before it's too late. Due to Yorick's passive (15% reduced damage taken at all times) he can safely build health without as much Armor and MR as other champions. This lets him build more flat health, increasing the AD gained from Atma's.
Finish off your Trinity Force. Tri-Force is a great item for any tanky melee champion, as it grants increased movespeed and a slow for sticking on targets, health (+AD from Atma), AD, and an improved Sheen proc.
After this, you can start building a selection of the following Armor and MR items depending on the enemy team. You can buy them before finishing off Tri-Force if you need to, but you shouldn't really have any problems staying alive unless an enemy carry gets fed.
Randuin's Omen and Sunfire Cape are both great Armor items for Yorick. The difference between the two is basically the choice of the Randuin's slowing utility, or Sunfire's damage. If you or your team having problems kiting, or being kited, take the Randuin. Otherwise take Sunfire.
Hexdrinker, I have found to be an absolute gem for Yorick. It supplies him with AD, and the shield it gives scales with his passive (taking reduced damage). Overall a fantastic magic defensive item which I take almost every game.
Force of Nature is a nice item to have if magic damage is a problem for you and Hexdrinker just isn't cutting it. Because you are so tanky and can stay in fights for so long, the health regen on FoN is very powerful, not to mention some more movement speed, which is always useful.
Get Banshee's Veil if you keep getting caught out of position by a stun or mage burst damage. As an added bonus, BV also gives some more health (AD via Atma) and mana.
Protect/help your jungler if they need it. After that, claim top lane and get ready to spank some ****heads with a huge spade.
The aim of Yorick's early game is to farm creeps while keeping your opponent from doing so. You do this by literally using your W and E (Q too if you can) on them whenever they are in range and you feel you have the mana to do so and still be safe. This will force them to either port back and heal, or die to your next harrass where you could get an Ignite kill.
Although you should try to not hit minions with the AoE from your W to prevent the lane from pushing, it doesn't really matter if you do. The reason being that Yorick is practically ungankable, due to his huge movement speed buff from Q, and constant slow on W.
Although Yorick is quite good at fighting right from level 1, he really holds his own once you get Sheen. At this point, you can keep farming your lane, gank other lanes, or try to force dragon.
Yorick is a perfect champion for mini-fights and ganks due to his reliable slow and massive damage. He can quite easily kill most carries and mages without much threat of dying unless he is outnumbered.
If you get a chance to intiate with your W onto a squishy, do it. Then train the **** out of them with all your spells until they die. Use your W to keep on enemies, or to help your team kite. Smash people up with Q and E, and ulti your AD carry or self.
With all 4 minions alive you are basically unkillable if you built well, so just keep hitting whoever you like during the fights. If the enemy focusses you, they won't kill you. If the enemy focusses your carries, you will kill them.
Yorick is currently a very powerful Tanky DPS champion, as he can stay in fights for a very long time, allowing him to do massive amounts of damage to the enemy team. You will make enemy squishy targets run in fear or just die. Either way, he is a great presence in both teamfights and laning, making him a great champion overall.