This is my jungling build for Nasus, by endgame you move extremely fast and are tanky and dealing pretty heavy dps with SS.

Start with your cloth armor and potions as most junglers, get madreds first so you can get blue around level 3 or 4, then farm up for your boots. Start building your Trinity Force and GA next, finish whichever you think you need more first, I usually get GA unless we have a proper main tank. Get wriggles whenever you feel necessary, if at all, to deny ganks. Once you have completed your boots, GA, and Trinity Force, just get PDs. Sell wriggles once you are full on everything else and get yet another PD, unless the wards are still necessary.

Basic. One in SS, max out spirit fire and wither first, whichever you prefer.

Start at mini golems, 2 easy stacks for SS right at the start, next go wraiths, then wolves, then you can take out the 2 helpers at blue and leave the actual buff for once you have madreds. By now you should be level 3 and can put in a few gank attempts, though its best to get madreds and blue buff before trying.

Ghost is entirely optional, I myself plan to try out flash and teleport for a while to see if either one is better.
Smite is, as always, a must.

FOCUS SQUISHIES. You can drop squishies extremely fast while absorbing a lot of damage with your ult active. If they are doing TONS of damage, you can skip a PD and get some more damage reduction.

Will add more to this as necessary.