Not Updated For Current Season
Nocturne is probably my favorite champion to come out for a long time, and for obvious reason. He's built for one purpose: to kill enemy champions. And he is quite successful to this end.
I use marks of alacrity to help is passive, seals of evasion for easier jungling, cdr glyphs for more spell spamming, and quints of desolation for easier jungling.
I recommend the standard 21-0-9 jungling masteries. Keep the damage up and experience flowing in.
The items I've suggested help both with jungling and for ganking. Nocturne will be fast, bursty, and capable of lifesteal and slow.
MAX OUT Q.
This skill is your bread. Spread on some butter (your e) and you can get anyone.
Smite is an absolute necessity for jungling. Nocturne has a tough time till he gets Madred's Razor.
Ghost can be swapped out for flash or exhaust, whatever you prefer for ganking. Exhaust combines well with your ult.