Nocturne Do's and Don'ts

I would like some help in figuring out as much about this eternal nightmare as possible. He's my favorite and most played champion, I love his mechanics and I want to know his do's and don'ts. Here is how i normally play him, start bot side for the best leash possible. If i'm blue team this means crugs, red, then blue, then I look to gank, if all lanes are pushed the I try to counter jungle by catching the enemy jungler off guard or stealing some of his camps. If purple it's the same but with gromp, blue, then red. I go or skirmisher's saber with devour asap to start stacking, then i fit bork and merc treads in when I can. When these are completed I start building tank, randuins if they have fed ad, banshees with fed ap, or I go into black cleaver if i'm really far ahead.

Any Higher elo nocturne players have any advice on him, especially as to when is he a good pick? against what junglers? What should I try to do or avoid as a nocturne player?
I have a good kda with him, but even when i get fed it's harder to carry some games than other, and I hear him spoken of as "A weaker rengar" a lot. Why do they make this connection? I want to improve my jungling, and I know that means opening my champion pool up more I have a lot of champions if you have any recommended picks that are a different type of play style than nocturne to help round out my play style please comment.