“The two big startup killers are when there’s just no market for what you are doing, and team problems. The first is very preventable: Do some lean startup testing, get in front of customers, and see the response. The other often stems from not thinking about potential problems up front, like what happens if one person leaves. Talk about them and, ideally, write things down.”
I couldn’t agree more. Plus I would add another mistake to the list (one which my dear friend Gary Whitehill is very fond of pointing out): Premature scaling.
All three are, as David mentions, very preventable.