One of the most important things to keep in mind when using any type of search engine, from Google to academic databases, is that search engines don't understand the meaning of language or comprehend your intentions - they simply search for the words you enter. For that reason, choosing good search terms and building good searches is the best way to ensure a successful search.
Here are a few strategies that can make your search more effective:
This video from Minitex presents some of the basic search strategies addressed above. Its focus is on using databases in the Electronic Library of Minnesota (ELM), but the strategies presented here are generally applicable to most databases you will encounter.