Read the abstract or summary to get a sense of whether the source might be useful.
Look at the citation to determine if the item is a format that you can use (book, magazine article, journal article, newspaper article, DVD, blog, etc.)
When you find one relevant source, use it to lead you to others on the same topic.
If you're not finding information that exactly matches your topic, use pieces of information from sources that are related. (Information quilting)