How should I change my skincare routine for summer?

The main changes are: switch to a lighter moisturizer (gel or water based instead of cream), use SPF 30+ sunscreen daily (even on cloudy days), add an antioxidant serum (vitamin C protects against sun damage), and increase cleansing frequency if you sweat more. You do not need to overhaul everything just adjust texture and add sun protection. Keep using retinol at night if you already do, but apply extra sunscreen the next morning.