What is the single advice that you'll give to a young first-time startup founder?

Understand monetization and compensation plans before you spend any time building a product or company. If you jump in with both feet, only to realize 12 months down the road that it will take another 5 years to generate a profit, you might find yourself in a situation where you run out of money to support yourself. Always evaluate your personal money situation before you assume any startup, team or product has any potential for growth.