Looking for touch-up tips

This is the first time I've really needed to post here, even though a lot of my questions about icons have been answered by sifting through the memories. I have found a predicament however that I just can't seem to find a solution for on my own.

I'm trying to make some icons, Daria icons in fact. The problem I am having is that while I know many tips and tricks to retouch actual photos of real people and make them look more appealing and add lovely colours and effects and all that wonderful stuff, I am severly lacking in knowledge when it comes to what to do in order to make my icons based on cartoons/anime look more appealing to the eye. I cannot seem to find the right combinations of brushes and techniques to make these bases stand out more and look like part of a whole icon instead of just this...screencap. It is by far one of the most frustrating things ever.

So my question, I suppose, is for all you icon makers out there that work with anime/cartoon screencaps. What are some techniques that you use in order to make your icons more whole? Are there any tutorials on specific retouching techniques, perhaps even some here in the memories of this community that have been applied to photos that could work just as well for cartoon caps? Any information anyone would be able to give me is welcome, I can never have too many options.

Thanks so much in advance. >_