You will run into difficulties if your question is too narrow (no results) or too broad (too many results). A clear and concise question will help you find that balance that is just right.
Are you hoping to find a guideline or meta-analysis of the literature on a question? Or do you want double-blinded randomized controlled trials? Knowing what you hope to see will help you use the best search terms and filters, and it will also help you recognize it when you see it.