Entrepreneur's important lessons in 20s ..

1. The difference between success and failure is self-confidence and persistence
2. Any limitations on personal growth are self-imposed
3. Networking is the key to success
4. Be passionate and decisive
5. Importance of surrounding yourself with people who will push you to be better
6. Need to hire people who are better than you
7. Learn to be patient
8. Learn the importance of asking yourself the hard questions
9. No matter what you're doing, you should always try your best
10. Don't let business get personal. It's just business. Shrug it off
11. Learn not to sell yourself short
12. There's no replacement for hard work
13. A fancy degree and natural talent don't entitle you to success
14. Being a leader can be lonely at times

ref: 

• http://www.businessinsider.com/best-lessons-entrepreneurs-learned-in-their-20s-2015-1
• http://www.entrepreneur.com/article/228134
• http://www.entrepreneur.com/article/237077