Sam Altman, president of seed accelerator Y-Combinator, recently asked a very basic question of his Twitter followers: What could someone have taught you in a class about startups that would have made you a better founder? Within half an hour, he'd received over 50 responses from entrepreneurs across the network. Some were concrete (e.g., "Taxes. How do they even work?"), while others were more abstract (e.g., "communication and empathy.") Here are 10 of the most noteworthy answers, from business owners who learned the hard way: 

1. How to network.

2. What "disruption" really means.

3. How to deal with the ups and downs (mental toughness), OKRs, and fundraising.

4. The importance of having separate legal counsel for each partner vs. legal counsel for the whole company.

5. How to hire and fire employees.

6. Taxes. How do they even work?

7. How fundraising works/Creative funding.

8. How to think about long-term strategy without derailing your focus.

9. Communication and empathy.

10. Get out of the class. Get your hands dirty. Start. 

What else would you add to the list? Respond to Altman's Twitter survey, or let us know with a comment below.