I've hired a number of PMs for my startup over the last 12months,and by far the most important thing that is overlooked (imo) is the ability to write good specs that are helpful for engineering. You can think of that as a sign that a PM can think like an engineer and communicate with engineers.<p>For people with PM experience, I'll ask them about the things they considered and documented in their last spec. If they think a spec is a list of bullet points, that's instant fail. If they considered all user flows in and out of the features, edge cases, user education, analytics/success metrics, release plan and time vs cost tradeoffs that's a win.