Remember, you are smarter than a computer. Use your intelligence.
Search engines are fast, but incredible dumb.
A search engine's ability to understand what you want is very limited. It will obediently look for occurrences of your keywords all over the Web, but it doesn't understand what your keywords mean or why they're important to you. To a search engine, a keyword is just a string of characters. Therefore, you must supply the brains. The search engine will supply the raw computing power.