Are you going to college? It's a whole new deal.
Seems there is no one thing you should do, it's a whole program. And it doesn't happen over night, so buckle up for a long ride. It's worth it.
What everybody says: work out, sign up for hobbies (even if you don't find femmes there hobbies make you interesting and help you grow), get out as much as possible. Learn a certain mindset.
There is no easy answer to this. If there was, everyone would be doing it. But there are things that will help you improve in the long run.