I think it's important to be able to separate business from friendship. The worst is when you're romantically involved with one of your start-up partners. Never

I think it's important to be able to separate business from friendship. The worst is when you're romantically involved with one of your start-up partners. Never do that. It also helps to start companies with people who are exceptionally laid-back, but you have to also realize that with that sometimes comes laziness. It's hard to find teammates who are both laid-back and highly driven/motivated, but when you do, they're solid gold. Whether you're friends before/during/after your endeavors is immaterial at that point.