I think my best single bit of advice is: think it through.

Decide why you're doing things. You'll be able to pull off things you never expected, with a some deep thought and a good plan. Plan your career, your finances. If it's your thing, plan what kind of person you'll meet and share a life with. Plan to maintenance your relationships.

Plan for problems, and disasters, because you will have many. Friends will die, plans will fail, money will be lost. A little planning will help you survive those storms.

Take pictures of yourself and what you're doing. I wish I had more.