Searching the databases is a little like looking for love.... sometimes what you're looking for falls in your lap, sometimes you don't know what you're looking for until you find it, sometimes finding what you want takes lot of trial and error.
So, a few tips...
Don't settle for "good enough" -- keep searching until you find what you really want.
Try something new if your search isn't working - new database, new search terms, maybe a new way of looking at your topic?
And finally, don't be afraid to ask for help! Contact a librarian, that's what we're here for.