* Try new things, join groups, stick your neck out. Don't find out you really prefer [X] or [Y] when you're 40, figure it out when you're 19. College fencing, for example, opened a whole world for me, like SCA, blacksmithing, etc. It's always going to be awkward joining/hanging out w/ a new group, just be patient and keep going.

* Spend as little time in your dorm as possible. Be out with people, read a book in the library or student union, join an intermural team, go to a party, whatever. Don't fall into the Weed-And-Vidya-Game pattern that college types tend to have. I suspect one of the reasons many dorms make students share a room is to force this.

* Be willing to say no to a course of study, or even to college. It's not for everyone, and I hate that we force people into it even if they don't have the money/interest/aptitude for it. The best-off people I know are CS grads, but several grads are not making great cash. Meanwhile I know (hired) electricians making north of six-figures, and I know a couple plumbers who are doing quite well.

* Most of the couples who got married after college are now divorced; most of the couples I knew in college split before graduation. Some are still a thing and happy, but the takeaway is don't limit yourself because of relationships. Date around if you can.