Although the first thing that comes to our minds is getting burnt when we hear the term excessive sun exposure, this should be the least of our concerns. In fact, being overly exposed to sun rays can be our skin’s worst enemy, as the cellular damage caused by it can lead to all signs of premature aging (ex. brown spots, wrinkles, etc…) and even up to skin cancer in some cases. 
Therefore, if you want to keep your young looks as long as you can and most importantly stay healthy, the first step would be to wear SPF (letters you will find on many of the available products in the market, that are designed to provide protection from the sun damage). SPF (Sun Protection Factor) is usually followed by a number that doesn’t really reflect the level of protection as most of us would think but in fact the duration of protection.
For example, while SPF 30+ guards against 96.7% of Ultraviolet rays, SPF 50+ increases that to 98% only. 
Meanwhile, if you normally get sunburnt after spending 10 mins in the sun, a product that says SPF 30+ will multiply that duration by 30 giving you almost 4 hours of protection. 
This means that a higher SPF product won’t really protect your skin better but rather for a longer time.

Having shared this with you, below are some tips to enable you to choose & apply the kind of sun protection you actually need:
1- Make sure it provides protection against both UVA (ultraviolet A) and UVB (ultraviolet B) rays. The first is responsible for sunburns while the latter can cause skin damage that leads to wrinkles.
2- Remember to a- Apply a generous amount of sunblock to all parts of your skin, even your lips. And yes, they do make products for lips that contain SPF. b- Reapply your sunblock if you are spending a long time outdoors to obtain maximum protection. 
Remember girls, to always wear sunscreen.