I only used the smudge tool a couple of times, I swear! Lol. This was done mainly with the paintbrush and the eraser tool, and yes, smudge, once or twice.
This is a great start. =) My best advice is to stay away from the smudge tool. It makes eveything blurry unless that's the intended effect. Try using a smaller brush sixe and play around with the opacities a bit. You'll see a lot of improvement! ;-)