background lacks depth, dont use filters, unless you use the GOOD ones for image fixing, and not screwing... colors look like barf. sorry if that may seem harsh, but it's the ONLY way you will get better, besides practice.
Not even. I suggest going for a more simpler technique. Just use an even brush pattern, I doubt you'd get lighting and such right off to make it look good, just do a simple brush back and go from there.