Don't know if I am experienced enough to give any advices but still:
1. Whenever doing freelance work, always take some advance payments, even its for your friends.
2. Use git even if you think it doesn't apply to you. I started really late.
3. Contribute to open source. You grow when the community grows.
4. Be humble even if you are the best there is!
5. Whenever you feel you are tired of this shit, remember why you started. Don't give up!

Most importantly, take time for yourself, family and friends. It won't be lines of code that you remember on your death bed!