Yea, as a beginner that's what to be expected. Given your experience level, it's pretty decent.
A few tips:
Use your layers and transparency settings. Don't color the picture itself, color a layer above the picture then lower it's transparency to let the lines bleed through. Then you simply have to clean up with the erase tool where needed. Each time you switch colors add a new layer. When you get the look you want you can always merge the layers down.
Also, when you colored the guys hair. Next step should have been to select the air-brush tool (that should become one of your favorite tools) and make the color a little darker, then start creating your shadows. keep making the color darker and darker, each time coloring less surface area until you have a really nice blend.
I don't use photoshop, nor do I mess with coloring mangas, but that's basic gfx design tips for coloring any type of renders.