Yeah, I know, it's a pain, and I get lazy too, but always try to wash your face every night with a gentle cleanser. I like Clean and Clear Essentials Foaming Facial Cleanser for sensitive skin.
If you are really tired, just use a facial cleansing wipe.
2.) Moisturize!
Yes, even in summer. Yes, even if you have oily skin. Use an non-irritating oil-free moisturizer designed for your skin type. I like CeraVe PM facial moisturizer.
3.) Glowy is Good
Glowy, dewy skin always looks good. Use a bit of highlighter on the corners of your eyes and on your cheekbones.
4.) Blush from within
Apply your blush after foundation, but then go back and put a little more foundation/powder over your blush to make it look like it's emanating from your skin, not just resting on top of it.
5.) Sunscreen Up!
Yes, I know there's nothing better than tan skin in the summer. But plenty of things are better than premature aging and melanoma (skin cancer). So cover yourself in sunscreen at least every hour or so that you spend at the beach. If you really want that tan, try Jergens Natural Glow. Or better yet, embrace your fairness. Maybe you could start a trend.