First i would like to say that Olaf is a pretty easy champ to get a handle of once you start playing him, and that if you start snowballing there is almost no stopping you.

Also i know that this is an expensive build but its worth it.

For Marks i like to take "Greater Mark of Strength" because of Olaf's passive and it becomes easy to try and get that first blood and it is also easier to last hit minions if you have trouble doing that.
For Seals i like to take "Greater Seal of Resilience" just for that extra survivability.
For Glyphs i like to take "Greater Glyph of Shielding" also just because of the survivability.
For Quintessences i like to take "Greater Quintessence of Desolation" just gor that extra armor pen that can help you kill people faster, it really comes in handy early game when you try and keep poking the enemy to stay away so they can't farm.

You should always get your Q first because it lets you get that early damage on them and it also keeps them at bay so you can get your farm. The next one will you want to get is W and this is the one you want to max out first because it does True Dmg which ignores armor and magic resist, you will want to max out Q second because you probably won't encounter any "real" fights until mid or late game.

"Ghost"- I like ghost because it helps offensively and defensively. For offensively it can be used to gank really well and stay on them to do continuous damage, and for Defensively if you use it to combine it with your ult it is almost impossible to catch you.

"Ignite"- I like ignite because if someone has alot of healing effects such as Volibear then you could use it on him to reduces his healing when he goes under 30% health and it also helps you finish off enemys that you dont want to chase or can't chase.

"Exhaust" - Sometimes i like to use this because it is good for anyone who is very aggresive and anyonw who is very offensive. Since exhaust slows thier movement speed and attack speed this lets you dominate them in a a fight. it would be smart to use this on their carry at the beginning of the team fight so the dmg trhey can inflict is minimal.

Pro

• Hard to Kill
• Deals True Damage
• Un CC able (When ult is up)
• His Passive is amazing
• He is OP
• Has an awesome slow

Cons

• hard to land Q if new to Olaf
• Deals dmg to himself with his E

In top lane you are gonna want to try and get everyminion kill that you can possible get and try and kill your oppenent at the same time so i like to try and kill the minions and hit the enemy with the same q so its like hitting 2 birds with 1 stone but i only do that if the minions between us are about to die, otherwise i just last hit them and throw my axe at them whenever i can. Also since olaf can do harass quite well you are gonna need to ward a lot because their top lane is gonna be asking for help and you want to be ready when he comes to help. The bushes that i ussualy ward are the tri bush on their side and the bush right outside your lane in the river so you can see him coming no matter what angle he decideds to come at you from. Sometimes if i have enough gold i put a ward near the blue exit and baron so i can see if mid is coming to help

In team fights your going to want to initiate with your Q, also if you want to engage them first then it would be smart to use your ult so you dont get caught by a snare, fear etc. Also if you want to get in and out really quick you could use ghost if you wanted. Once the team fight has started just focus their carry so their total dmg output wont be very high, so then you can just brezze right through the rest of them.

Play Video
This is gameplay footage of Vern, you can find his guide at " Vern's guide"

This footage shows him using his ult to counter Cassiopeia's ult in order to kill her. This just goes to show how useful Olaf's ultimate is.