The hardest thing about fairies is that there is a lot of differnt types. Whether your fairy is evil, good, foresty, or anything from nture could make a big differnce. Typically they fit their surroundings. A fire fariy will live in a volcanoe or near one or in a very hot climate, they would have fire colored wings, orange hair, and are hot tempered. Like that, thy fit their environment in such away that it describes every part of them. Though there are many cases where a fairy is decided in a differnt way, such as for example you'd like to write about one, which I believe is your reasoning. The fairy can be portrayed however you'd like. Make them look like the opposite of their surroundings, make them viscious and mean, make them humanid, make them small people with wings. It all depends on you and your story.