Thanks, how I said i didn't have enought time, I'd like to work more on it but I had less than one day to do it :s 

Sometimes it's pretty hard to finish doing something, like when I was doing the sprite, at first moment I thought it was horrible and I almost stopped doing it, but looking after finished it looks something nice, and this happens to everything I do, when I start it, most of the time I don't like and I abandon it :s 

Thanks for the tips ;DD

Some tips that I can think of for this.

When doing different layers of background to show distance, it's common to reduce the saturation with distance. Kind of like the trees in your avatar.

Try to keep consistency with the details. Although the character stands out more, it does so too much and looks out of place. Adding more clusters to the background and forground with highlights and shadows should help. On the other hand, less clusters on the character would help too, but the background and foreground still need more details.

These things will come naturally over time as you practice.

If possible give me tips!