Avoid frequent eye strain, for the long-term health of your eyes. While the occasional squinting isn't going to do much harm, if you're doing it on a daily basis, your vision could be in danger. Experts recommend getting an exam to determine if your strain is due to needing glasses and to otherwise go easy on your eyes.
What you eat is very important to the health of your eyes. A diet that is rich in vitamin A and omega-3 fatty acids are helpful to good eyesight. Many vegetables like carrots and broccoli are rich in vitamin A. Fish and nuts can provide you with the omega-3 that you need.
If you're going out into strong sunshine for any length of time, make sure you wear a hat with a wide brim. Although sunglasses do protect your eyes to a certain extent, a hat will keep the sun out of them completely. Your eyelids can be particularly vulnerable to melanoma, something that you can avoid simply by sporting a hat.