First you must have determined the concept of the problem or topic. This will enable you to identify keywords, which can become a beginning for finding relevant information and literature. Recent information is predominantly available in the English language.
After identifying relevant keywords, you should also be aware of synonyms and related terms. It is possible that some synonyms are more relevant in your specific subject field and would therefore result in more relevant hits.
Examples:
improperly posed problems --> ill-posed problems
ondelette --> wavelet
Sometimes it is necessary to broaden or to narrow your topic:
splines broadened to numerical approximation
web programming narrowed to (x)html, xml, php, cgi.
mathematical economics narrowed to price, market, risk, resource, portfolio, investment.
Test your keywords and the main concepts of your topic by looking them up in the appropriate background sources.
