Someone's post made me think a thread might be useful on this.
First off, the starting link. Kinda a neat idea, given how hard it can be to find female character art in clothes:
http://womenfighters.tumblr.com/
Myself, I usually start with Danbooru.org and Safebooru.org, using a couple of tags to try and track something similar to my thoughts. Then usually hit deviantart to see if they got something there. If it's a male character, I start at deviantart, since finding male art in the booru is almost a waste of hunting time.