Keyword searching is a strategy that you can use in a lot of different places - in catalogs, in databases, on the web, etc. Often we start with certain keywords in mind, and are disappointed when those keywords don't immediately return exactly what we need. It's useful to develop alternative keywords so that when you hit roadblocks, you have something else to try, and you can find related results that may be described in slightly different ways.
Keywords to think about for costume design:
Binoculars will not usually help you find costume design resources, but much like the man with the binoculars, you will have better luck if you prepare yourself for your search.