A hat with at least a 2- to 3-inch brim all around is ideal because it protects areas that are often exposed to intense sun, such as the ears, eyes, forehead, nose, and scalp. A dark, non-reflective underside to the brim can also help lower the amount of UV rays reaching the face from reflective surfaces such as water. A shade cap (which looks like a baseball cap with about 7 inches of fabric draping down the sides and back) also is good, and will provide more protection for the neck. These are often sold in sports and outdoor supply stores. If you don’t have a shade cap (or another good hat) available, you can make one by wearing a large handkerchief or bandana under a baseball cap.
A baseball cap protects the front and top of the head but not the neck or the ears, where skin cancers commonly develop. Straw hats are not as protective as hats made of tightly woven fabric.
Also many sunscreens are good for blocking the rays that cause sunburn but not the UVA rays that cause cancer and skin damage. Your sunscreen may list a high number for "protection" but it may only apply to the screening of burning UVB rays.
Many sunscreens do not block UVA radiation, which does not cause sunburn but can increase the rate of melanoma and photodermatitis, so people using sunscreens may be exposed to high UVA levels without realizing it. The use of broad-spectrum (UVA/UVB) sunscreens can address this concern. Diligent use of sunscreen can also slow or temporarily prevent the development of wrinkles and sagging skin.