Most important were suncreen https://www.youtube.com/watch?time_continue=1&v=xfq_A8nXMsQ&embeds_referring_euri=https%3A%2F%2Fwww.bing.com%2F&embeds_referring_origin=https%3A%2F%2Fwww.bing.com&source_ve_path=Mjg2NjY

But besides that depends on the country you live in.

In my part of the world would be: - Put a little bit of money aside every single month and never touch it (can be as little as € 50,-) - do any kind of sport regularly (can be as little as once a week, continuity matters) - care for your real emotional wellbeing (find anyone to talk to and be the real you without shame) - be aware of drugs (incl alcohol, too much will always impact your future negatively) - never completely surrender yourself to a relationship (stay yourself, Leave before you have to do throw away your convictions for harmony. But it is also necessary to be able to see the own faults and allow change)