Most people have become more aware of skin harming behavoir. Nevertheless, here are a few thoughts. Especially in the mountains, the sun's radiation is significantly higher (even more so in winter or next to water due to the reflection by the snow). I noticed this despite all the sunscreen measures when I had a sunburn - beware - INSIDE the nostrils after an avalanche course. OK, yep, I certainly didn't apply sunscreen there. But since then, I also take care of this area diligently.
It is better to apply sunscreen again, even if it is sticky and annoying. Pay attention to areas that are not covered by a normal baseball cap, such as the back of the neck, ears, and tip of the nose. The backs of the hands are also almost constantly exposed to the sun. It is better to choose a sun hat with a brim, even if it doesn't make you look so cool. Which sunscreen is preferred is up to you. I have stopped using natural creams because my skin type is simply too fair. It is important to choose at least SPF 50. There are special creams for existing skin damage - I don't know if SPF 100 brings more benefits (the SPF number only indicates how long you can stay in the sun compared to being unprotected), but if in doubt, ask your dermatologist.Even better: wear long-sleeved clothing and shirts with a tight neckline. There are also special UV shirts. For summer, I, like with socks, am a fan of merino wool - yes, even in summer. There are great brands that produce very thin shirts - yes, the investment is really worth it - one advantage: it doesn't smell even with sweat (if it does, I've doubts about the quality).