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 for 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.