Many photographers go to conventions, comic-cons, or similar events and make images of the participants. Some outfits are very elaborate, and some of the participants REALLY get into their character. So the question that may occur to you is who is the character? Not just what the costume represents, but what makes the character special enough that someone may want to model that outfit. If you understand that, chances are you will really come out with some outstanding images.
For example, Catwoman (above) has endured in the Batman world for many years. The costume is certainly very well done, and the participant may even want images of the entire costume not already taken by a camera phone. The way the costume fits and is designed may give you ideas for future concepts. But clearly there is much more to Catwoman that just the outfit. From the almost tame nature of the cat to the more aggressive and dominant characteristics that has made Catwoman famous within the Batman world.
Conventions are often very crowded with very little room at times, not to mention most participants may not want to spend hours posing for pictures. If you as a photographer, like a character, it may help if you spend a little time with the con-goer to find out about not only the character being played, by what makes the character special to the person who is modeling the outfit.
One you have this rapport, you may get dynamic images that you thought may not have even been possible!
-Bob Barford is a published photographer based in Southern PA.