I've always been someone who learns by messing up. That said, all my screw ups have been relatively small, and I'm not sure if I would have ended up here had I not been through them.

I can think of a couple:

• Not learning accounting soon enough. I had zero clue how financial statements worked or how companies were measured until a couple years ago. I'd basically just do the mental math: was there more money in the bank than last month. Yes? Success! Now I advise anybody to spend an hour or two learning how a P&L/income statement works, and ensuring that you get a great bookkeeper early on.

• Not charging enough. We used hourly billing for a long time, and it cost us a hell of a lot of money. When you work hourly, clients feel like they own you and it can breed bad behaviour.

• Not taking equity in more startups we've worked with. We've always chosen to take cash instead of equity. Longterm, I think this has paid off and allowed us to build our own products with that cash, but there are a few situations where I wish I'd jumped on the equity train. This is a really tough one though—equity is glorified toilet paper in most cases.

• Feeling lazy and beating myself up for hiring people. I used to beat myself up about hiring others to do design work I felt that I could/should be doing. Now I look back and it seems insane, but it really does feel like cheating at first.

• Not learning how to negotiate. In the early days, any good business person would try to haggle with me on our rates. I'd immediately get offended, but roll over and lose out as a result. I felt that negotiation was dirty, and didn't realize that it was a totally normal part of doing business with people. People expect to be negotiated with, and when you don't, it can actually weird people out. This douchey-looking book was super helpful.