Well, yes, covering up with long sleeves and trousers will definitely lessen the risk to your skin, but clothes are not an impermeable barrier. A white T-shirt offers a protection index of around six, which lessens to three if you get it wet. The protection afforded by darker colours can rise to as much as a ten. Not surprisingly, denim offers one of the highest levels of sun protection, though it's probably not the most comfortable choice for a sunny day.
There was a time when a lady wouldn't have dreamed of going out in the sunshine without a hat. Today, this summer fashion item is a wise choice to help protect your skin. The denser the fabric, the higher the sun protection and, clearly, the wider the brim, the better. The shade cast should be enough to protect ears, nose and shoulders.
It's not just our skin that suffers from the sun: eyes can be seriously damaged by over-exposure to too bright light. It's important, then, to use sunglasses with lenses of reasonable quality, so make sure they are labelled with CE certification. Don't kid yourself that the cheap imitations from the market are just as good: your eyes have to last you a lifetime, so take care of them.
And finally... Keep in the shade! Remember that the sun's rays are reflected from different surfaces, particularly clear water and white sand. So even if you're in the shade, you'll be getting a sun tan, it'll just take a bit longer and be less aggressive to your skin.