When I think cosplay, I think about geeks dressed up as characters that they like from either an anime, comic, video game, or other pop culture media. For those of you who do this, don't take offense, as I consider myself to be a geek too. Just not enough to dress up
Anyhow, it helps as a photographer to know a little about the series in which the cosplayer is attempting to portray. For example, I wouldn't shoot someone dressed up from a medieval series in front of a car or something modern. Get what I mean? You should try to be true as you can to the source material. If you don't know anything about a particular series, the cosplayer should be able to fill you in.
As for "the look" of cosplay, I don't there's a certain framing, pose, or lens that's exactly required. If anything, you just want to make sure the photograph is a good representation of the series and character being depicted. Part of the responsibility is on you as the photographer, in coming up with composition and backdrops, but most of the burden is on the cosplayer. A good cosplayer should be meticulous about their costume's accuracy and their ability to keep in character. If your model/subject was neither, you'll have a difficult time coming up with a good cosplay photo shoot.