4. You’re not using enough.
Few people apply enough sunscreen. Sunscreen should be applied a half hour before sun exposure so it has time to really absorb into your skin. And be generous! Properly applied sunscreen properly should leave a film on the skin. When in doubt, apply more.
5. You’re not applying sunscreen often enough.
Most products suggest reapplying every 2-4 hours. However, recent studies have shown that applying sunscreen every 20-30 minutes is more effective. Apply even more frequently if the product is diluted by water or perspiration.