The key to summer makeup - less is more. Think, tinted moisturizers with an SPF. A little bronzer. Self tanners for the face and body. Powder is your friend, as it helps absorb shine from excess oil and perspiration. Powder-free blotting papers are perfect for removing excess shine and oil without looking caked on. Sheer lip tints look just right, and are a better choice for summer than more opaque formulas.
This story from Beauty Press is spot on with tips and techniques for summer makeup. I especially like the blue liner. For something more subtle, you can apply, then smudge with a liner smudging brush. Or apply liner on the top lid only.