like i said to you befor a couple of steps and it can be really good
-Make renders bigger,
-Blend them in with adding colors not taking away.
-Color with Color balance, Imo Mutli Coloring is overrated.
-use brushing with softlight to highlight and darken areas.
-1 px boarders help alot.

i think if you take some time on learning photoshop some more you will get really good, no body is good when they start.