Some thoughts:
- Cofounders are high stress and high time relationships. You want to find someone who doesn't burn everything down every time they get stressed. Finding someone who deals with stress in a healthy way is huge.
- Don't let the small things get in the way of the big things. You have to have tolerance for each other's mistakes. This was a huge problem for me and a previous cofounder. The way I handle it now with my cofounder is we set a price on mistakes. If you want to take a $1,000 risk, we don't even discuss it. A $10,000, we talk about.
- I generally prefer people driven by discipline than passion. Passion cracks under pressure. Discipline keeps working.
- Ego. Find someone who doesn't think they're god. I know in the SV hype messiah driven world of startups everyone tries to be the prophet. Avoid these people. For me, someone who has confidence but not arrogance is huge.