Well Its good to hear that you are concern at such an early age! I am 22 so and graduated and If I can reset my last 4 years, I'll do following things -
1) Read a lot: lots of books, news, trending topics around the world in spare time instead of fooling with friends. It'll benefit once you start your professional life.
2) Learn something (useful) apart from your major: Yes that's something people ignore in their adulthood, they just keep putting their time in their passion. I am not saying that's bad but you should give some time to something else like if you are into business major then it'll not harm you to learn graphic designing or history course. It'll broaden your scope of knowledge!
3) Give time to family: That's obvious isn't it? Yeah but people in their early adulthood are so much into friends/gf/bf, studies,etc that we forgot about them, we barely talk each day for 5min or maybe less than that. I can tell you'll regret once you'll not have time to do a thing apart from job and all that you'll miss your family the most. So make a habit of calling your family, you mom / dad / bro/sis daily even for few minutes. You'll feel better everyday!
4) Invest your time and money on both health and wealth: Investing early is always good habit, soon you start investing soon you'll get the results so start investing not just in your wealth but health also.