Don't have personal relationships at work. That old saying, don't shit on your doorstep.
Don't be an open book at work. The people you think are friends are colleagues who may use that information against you further down the line. Keep it pleasant but professional.
It's okay to be out of your comfort zone sometimes. Playing it safe makes you miss so many opportunities and experiences.
Save money. Don't make others rich by buying crap. Really make every purchase count. Don't be stingy, but don't be wasteful.
Pay into a pension as soon as you can. Retirement can seem ages away but it comes sooner than you think. And a proper provision allows you to think of retirement at an earlier age.
Keep flexible - in mind and body. Don't get stuck in your ways, or keep looking back. Exercise for strength and suppleness.
Don't get overweight or unfit. So easy to do, so hard to lose or get fit again.
Don't compare yourself to others, be your own person. Just concentrate on who you are, what your values are, your own journey. Don't feel inferior to anybody.
Learn languages.
Don't allow someone's opinion of you to destroy your piece of mind. Their opinion of you is none of your business, your opinion of you is the only one that counts.
Don't put men on pedestals. This is not a man hating comment just an observation about all the angst we go through over them. They really are not worth all the hand wringing. Don't prioritise them over friends or anything else you enjoy doing.
Don't be seduced by screen time. Read a book instead.
Learn to drive early.
See as many new places as you can.