The databases where you can find articles are in alphabetical order and NOT according to importance, since each researcher will have a different thesis and needs.
Take a moment to think about your topic. Define your topic by asking yourself a set of questions. Turn your topic into a research question (a thesis topic). Think of words and phrases to use in a search of information regarding your topic. If nothing works, change your search terms to find more specific or more general information. Remember you can always ask for research help from a librarian.