One simple thing one can do (besides always using a good UVA/UVB sunblock lotion) is to wear a wide brimmed hat when out in the sun.
The edges of your ears are a prime location for the development of skin cancers. Because of the increased blood supply and tissue structure, skin cancers located on the edges of the ear are hard to treat and cure. Cancers located on the edges of the ear also tend to spread inward quickly more quickly than a skin cancer located on the body trunk. Wearing a brimmed hat besides suntan lotion will stop this particular risk factor completely.