Find a retail clothing store that sells clothes with minimal prints and logos, and with a lot of different color choices for each item of clothing. It is easier to make your own costume if your clothing has no logos to cover. American Apparel is a retail store with which to start your search, because it has many kinds of basic clothing items in a wide range of colors.
Choose the Hawkgirl outfit you would like to base your costume on. Through the years, Hawkgirl's costume has changed a few times, especially the upper body section of her outfit. You can find these outfits through many major search engines.
Buy your costume pieces from clothing stores. The body of Hawkgirl's costume consists of a yellow top, green leggings, and red and yellow boots. Online costume stores often sell affordable shoes and boots for general superhero costumes, which can be customized and dyed according to your costume needs.
Decide whether you want to make or buy Hawkgirl's costume wings, which are attached to her back. If you are planning to go to a crowded party, oversized and elaborate wings may not be the best idea, and you may want to forego the wings altogether. Costume wings that attach at the shoulder can be ordered at online costume stores or found in costume retail stores, or can be made with cardboard and glue.
Make Hawkgirl's yellow and black mask from cardboard and construction paper. If you buy a basic face mask, you can glue construction paper on it in the shape of Hawkgirl's mask. Refer to the pictures of Hawkgirl you would like to copy as a basis for your mask.
Create Hawkgirl's mace using a paper towel tube and newspaper. You can use paper mache to cover and color the basic shape and to make a lightweight yet strong structure.