A: Always apply sunscreen first, says Robyn Gmyrek, MD, assistant clinical professor of dermatology at Columbia University. Apply it to clean skin, and allow it to penetrate for 20 minutes before sun exposure. Choose a broad-spectrum sunscreen with an SPF 15 or higher, and reapply it at least every two hours if you're outside. Gmyrek recommends those with Mexoryl SX (found in La Roche-Posay Anthelios 40 Sunscreen, $30), Helioplex (in Neutrogena Age Shield Face Sunblock SPF 90+, $9.50), and any sunscreen with titanium dioxide or zinc oxide (like Dr. Perry's Natural Block, $20, or SkinCeuticals Daily Sun Defense SPF 20, $30).
Bottom line: If you use a cream sunscreen, you may be able to skip moisturizer; be sure to use enough (about half a teaspoon) to get adequate protection.