Follow these rules to choose the best keywords.

1.   Eliminate prepositions, conjunctions, adjectives, adverbs and articles.

2.   Focus on nouns.

3.   Combine keywords into natural phrases.

4.   Use wildcards to pick up variations.

5.   Use synonyms via the Boolean OR operator.

6.   Choose 6 to 8 words total.

7.   Distinguish concepts with parentheses.

8.   Order concepts with main idea first.

9.   Join concepts with the Boolean AND operator.

10.  Watch out for case-sensitive search engines!