Nasus was the first champion i bought, so he was a big impact on me, when i started i mained top lane but when i noticed there was a huge gap in support and in jungle i quickly figured out ON MY OWN how to do both roles, and really i do jungle routes to figure out how to do the weird junglers like Nasus and TF. This is how i play him so don't hate on me for wrecking face with him when i was level 2.

Get q for the stacks the go strait to w for hitting multiple targets at once, remember that you w will do damage when it lands on a target then slowly does the same amount of damage over time. So you should fight inside your w for the max damage at early levels.

Either way you start do "gronk"(or what ever replaced the single wraith), or do golems. after that if you do golems do red, or if "gronk" do blue. Leashes might help with golems or white camp, but you have a small but of life steal and that means a small leash vs a big leash might not matter.

Getting Q stacks is key, get as many as you can by last hitting creeps, towers, champions, monsters. Once you get you q stacks to about 1000 just use it for damage if its early game, in late game keep farming q stacks.

Ap or Ad runes are good, maybe getting health regen or mana regen will help, and just getting health or mana will work.

The masteries include ad or ap which one you want, some speed and mana regen for if you start on the red buff side and armor is good for the early levels.

For all of them i get some tanky items to help against surviving a fight and being a "tank" for your team. Rod of Ages will give you the biggest power spike you can get, so try and get that after you get your jungle item.

If there are any questions or comments tell me, or if there is anything you want me to add or you dislike(and why) i will gladly take some help from others. And to conclude nasus is op and if you know how to play him there is no doubt you will win your lane.