This is a really lovely picture of Yuno, and it reminds me on drawing her myself sometime aswell. ( ´・ｖ・)♥
I love how you did her expression, and especially her eyes. With this black background and the "fade to black" effect it looks like Yuno is either stepping out of the shadows, quite suitable in my opinion. The soft coloring blends in well with the colored lineout, however I believe the shading could have been a little more darker - or it's simply my laptop's screens fault, I wouldn't deny that at all (⌒_⌒ The splattered blood is a nice addition as well.
All together this is a really nice fanart, and instantly going into my favourites (*´∀`*) Keep doing :3
I believe most people do it like this, so it's nothing to be ashamed of I do it myself, because I feat that otherwise I mess up at some parts ^^ And you really did great on this picture, no need to worry (°￢°)