Be picky and careful in your evaluating. Constantly be evaluating the site for its authenticity and relevance. If you spend more that 15 min. following and searching a particular site and still have not found what you want, give up on that one and try another. Be very careful not to waste your time on poorly developed sites. There are many good ones out there, but for every good one there are 3-4 poor ones.
Many search engines offer help on how to best use their search engine.
Don't be afraid to click on their help links and read up on how to effectively use their engine. It can greatly improve your results. Try many different search engines. You will find some that work better for you than others.