The research process is not a straight line - it can twist and turn as you learn more. Don't be afraid to follow up on information that interests you - it's easier to write about a topic if you're interested in it!
Be willing to tweak your vocabulary - authors may use different words that mean the same thing (i.e. illustrator, artist, draftsman, etc.)
Read article abstracts to ensure they will work for your paper - don't just grab the first articles that include your search terms