Be persistent in your searching.
Try both keyword and subject searching.
Narrow a search by using subject headings. Locate subject headings by looking at the descriptors associated with pertinent articles and books.
The National Library of Medicine's Medical Subject Headings (MeSH) is the standard vocabulary for disease, drug, anatomical, and physiological concepts. To find the correct MeSH terms in the Medline database, click on the MeSH rectangle, type in a term and press "Browse".
Try synonyms (AIDS OR Acquired Immune Deficiency Syndrome).
Try both singular and plural forms of words. Use an "*" at the end of a word in Academic Search Complete to get a variety of word endings.
If searching a compound word, try it as one word and as two words (e.g. rain forest or rainforest) to see which retrieves the most useful results.