Mark Henricks interviews John Osher who discusses the 17 most common mistakes startups make, along with 5 must dos to win:

Mistake 1: Failing to spend enough time researching the business idea to see if it’s viable. “This is really the most important mistake of all. They say 9 [out] of 10 entrepreneurs fail because they’re undercapitalized or have the wrong people. I say 9 [out] of 10 people fail because their original concept is not viable. They want to be in business so much that they often don’t do the work they need to do ahead of time, so everything they do is doomed. They can be very talented, do everything else right, and fail because they have ideas that are flawed.”