It really all comes down to coloring. I find a coloring I really like, save it, and adapt it to the icon. I've got about 25 saved .psp's that I use over and over; sometimes I mix the ideas together, lower or raise settings, etc.
I also like visiting icon_tutorial @ lj and seeing what people have posted there. For every 100 posts or so, I can find about 10 or 15 colorings that I really like. Then adapt them to meet my needs.
I doubt that answered your question, but I tried! :D