As the weather heats up, you have to adapt your skincare routine to the changes in temperature and humidity (not to mention activities!). In the summertime, it’s all about swapping out heavy products that can combine with sweat and turn your face into an oil slick, clogging your pores and leading to breakouts. You’ll look fresher and your makeup will last longer if you swap your heavy facial cream for a lightweight formula. You can also eliminate an entire step from your routine -- and beauty product clutter -- with a combination sunscreen and moisturizer. Dr. Wu likes Aveeno Smart Essentials Daily Moisturizing Lotion with SPF 30. Her skin-saving advice: "Only apply this product to dry skin patches and avoid the oilier T-zone."