- Get fit: go to the gym regularly, eat healthily, sleep well. It's amazing how different peoples' first impressions of you will be if you're even a little bit well built.
- Learn life skills: cooking, seamstering (is that a word?)
- Travel somewhere very different to your home country for at least a month
- Try to start a company
- Learn the basics of a wide range of topics: politics, economics, philosophy, law, etc.
This is the stuff I would do if I could take a year out of university right now, some of it might apply to you too.
Parent had a lot of good advice. Take the time off to build some good life habits that will carry on past college.
I'd add a couple more
- Read everything you can in as wide a range of subjects as you can. Building a solid base of knowledge in a wide range of subjects will set you apart from your peers and give you a strong foundation for linking disparate ideas in college. You'll get a lot more out of your classes if you understand how ideas fit into the bigger picture than if you limit yourself what your professor tells you.
- Find a mentor who can help guide you and give you suggestions for what to read and study as well as take a long term interest in your development personally and professionally. They can be invaluable aids.
- Invest in relationships. You'll have a lot of free time and flexibility to spend time with people, do it. Build long lasting friendships that will carry through college and beyond. They'll be there for you in good times or bad. It's time well spent.
- Learn life skills: cooking, seamstering (is that a word?)
- Travel somewhere very different to your home country for at least a month
- Try to start a company
- Learn the basics of a wide range of topics: politics, economics, philosophy, law, etc.
This is the stuff I would do if I could take a year out of university right now, some of it might apply to you too.