Nocturne is unstoppable 1v1. Before attacking a champion ALWAYS cast Duskbringer. After about 3 auto attacks pop your Unspeakable Horror, or use it when the enemy starts to run away. You should always be dominating 1v1, but be sure not to push to hard early just last hit and if the enemy is pushing push them back.

Nocturne is an AMAZING farmer. If your passive is up cast Duskbringer into a group of enemy minions then auto attack away. Remember if an enemy champion is hiding behind a wall of minions pop your Duskbringer on him then you can go right through the minions.

There are many champions in League of Legends that you can always tell what spell they are gona cast. Lets say you see Ezreal charging his ulti, pop your Shroud of Darkness at the right time to block it. Or if you see an Ashe ulti flying after your 10hp team mate take the hit for him but block it with Shroud of Darkness.

This guide is very short but effective. Just try it and if your not a scrub you will see. Play smart and dont jump into a 3v1 ( you being the 1 ) at level 5. Save that for levels 16+. Always stay farmed and dont let enemy champions push you around 1v1 you are the king at 1v1. Enjoy :)