Wash your face first thing in the morning and at night. Avoid cream based cleansers unless you have really dry skin, because they tend to leave your skin oily. Also, exfoliate one to two times a week to get rid of dead skin cells, the exfoliation will also help keep your face look smooth and clear.
Of course, it's probably best to skip this if you're skin is naturally oily. But it's a great idea to moisturize your face in the morning (with a moisturizer that contains SPF) and evening, it's also a good idea to moisturize the rest of your body; arms, legs, etc. Moisturizing can also help some people clear up their acne - bonus!
Homemade face masks can be a great deep moisturizer as well!
Of course sunscreen can be sticky and stinky, but it's one of the most important things for the summer. The effects of excessive unprotected sun exposure - or even one really bad sunburn - can cause irreversible damage to your delicate skin. Finding high SPF can be a problem, and sometimes finding the right coverage is as well can be tricky, so talking to a pharmacist or a dermatologist might be helpful.
I hear "drink some more water" about 15 tines a day, and while I'd rather sip an iced coffee, I have to admit that staying hydrated is a great idea and does wonders for ones complex - especially during summer.
When you get bored of water, just add some lemon with cut up strawberries! There's tons of ways to spice up your H2O, especially if you're like me and find it difficult to consume 8+ glasses a day.
This isn't just a summertime rule, it applies to every season! Eating the right foods can help slow down aging, protect, and create glowing skin. Incorporate salmon, kiwi, nuts, blueberries and melon into your diet, as well as choosing a green tea over coffee.