Hi.
You were better off than I was when I started. Good job picking up skills like this!
Trust me, it takes time to pixel like those crazyass pixelpushers here.
Anyways:
I edited your picture. One aspect is that you use many unnecessary colors in your picture. DO learn to economize your colors. I managed to reduce your color count from 14 to 10. Colors that are extremely close together (in this picture's case, would be the multiple shades of gray that look alike), should be merged together.
As I use GraphicsGale, you can quickly "merge" two colors together by CTRL + dragging one color onto another (in other words, replacing a color with a copy of the other), and then, from the palette menu, merge similar colors together.
I also gave your picture a third dimension. I picked a random vanishing point and lined it up using that.
I varied the hues, and added some details to your controller. I also added some (not very good) texture to the dark "grip" pad... thing. (Yes, I used to have a NES...)