Do: Brainstorm various possible terms for your search. Choose the terms closest to what you are looking for and seem the most natural terms to describe the concepts.
diabetes, diabetes mellitus, diabetes mellitus type 2
elderly, aged, aging, seniors
Do: Combine concepts using AND/OR/NOT.
children AND obesity
"heart attack" OR "myocardial infarction"
Do: Add quotations marks around phrases to improve search results (or remove them to broaden your search).
"post-traumatic stress disorder"
Do: Revise your search terms based on other words you encounter in your research. Consider the intended audience of the website (general public vs. medical professionals) when deciding whether to use popular or media terms as your search keywords.
"heart attack" becomes "myocardial infarction"
Do: Resort your results by date/relevance. Do you want the most recent or the most relevant at the top?
Don't give up looking if your results aren't what you expect! Revise your terms or switch databases and keep looking!
Do: Ask for help if you're not finding what you're looking for!
The sources you use lend you the author's credibility and understanding of the subject--so find a knowledgeable expert! Research articles also provide you with evidence for the statements you are trying to make in your own writing.
A simple way to evaluate any information is to consider its credibility, content, and currency (the 3 C's). Consider: