Write down the question that you want your paper to answer.
How do double pane windows affect heat transfer?
Next, underline the key concepts in your question. These are usually the nouns, but they can include adjectives if they are part of a unique, vital phrase. You can also leave out words that are automatically associated with the more specific parts of a phrase--when you talk about double panes, for example, the concept of windows is assumed.
How do double pane windows affect heat transfer?
Looking only at the underlined words, use your formatting tricks to optimize your search.
Chunk them together with an AND, then do your search!
"double pane" AND "heat transfer"
Once your search is pulling up good results, click through on some of the article titles to see all of the information used to describe those articles--the metadata. Look for the subject terms or author-supplied keywords used to describe the articles that are best for your needs, then incorporate those terms into your search strategy.