Great post on Startupping in which entrepreneurs are asked about their best and worst decisions. Some that stayed with me:

Ross Mayfield - Biggest Mistake — Not taking bigger risks earlier.
Maybe because in hindsight all risks are clear, but I always find myself regretting not taking bigger risks earlier. For example, open sourcing the Socialtext code was something we waited on until the company had strong footing. Partially because we thought there would be cannibalization, partially because we were understaffed to really engage with the community. But I believe if we bought this bullet earlier in the history of the company we would be reaping better rewards. As a planning exercise, now I always try to ask two questions: “How could we take more risk?” and “What risk can we take that creates the greatest amount of options?” I find there is always a way to do a little more, in particular by getting past instinct to control prevalent in so many entrepreneurs.

John Battelle - Pick one constituency and stick to it. Very early on, we decided that FM would be “author driven”. We could have made the company “advertiser driven” but it struck me the core business had to do with the folks who produce the sites we work with. At Wired, it was all about the ideas. At the Standard, it was all about the journalism. One clear core driving force helps clarify decisions during the tough early years.

Dick Costolo - I’ve made loads of mistakes so I’ll try to think of one with a good lesson for startups - one of the biggest mistakes I made in a previous company was accepting a high dollar contract once for something that wasn’t core to the vision of the business we were running at the time. While the revenue initially feels great, there’s nothing worse than pursuing a piece of business that isn’t core to the startup’s vision.

I highly recommend this post since although experience is a valuable teacher, it’s far better to learn from the experiences of others where you can.