Number 1: Change you underwear every day!
My advice for you as you're turning 18, assuming this also means adulthood.
2. Mistakes are good as long as you learn from them.
3. Get out of your comfort zones, take risk, push your limits, and fail.
4. Cash is freedom. All financial systems and culture promote bigger, more, better, and credit. Credit leads to debt and ties you down from exploring true happiness.
5. Time is the most valuable and finite resource you own, at least until you go into debt. Don't waste it.
6. Memories are made living experiences, not buying things. Spend your time and money on experiences to enrich your life story.
7. Don't label people. Labeling and demonizing people who don't think like you is a societal trap. Everyone has a story so stay open and learn their story. Their story is where the magic happens.
Go forth young man and help make our world better.