Make sure your group has a unified vision about what they want. If one person wants a pretty place, and one person once a cheap place, they will block each other and you won't ever reach consensus. Not having a unified vision, and not realizing this, is where the majority of would-be co-housing communities fail. If there's something you want people to have as a house culture, make sure thats in agreement too. I personally requested that people be willing to chip in for a maid and hot tub and maintain a paleo 2.0 kitchen, and these things have all been adopted. Vision can include anything from over-arching life goals to never having dishes cluttering the sink. Explore what you really care about and make sure that everyone explicitly agrees to whatever goals are set and that no one is silently dissatisfied.

Succinctly put. A slight generalization on this formula seems important for "group projects in general" modulo the need for detailed and realistic knowledge of predictably satisfying details in the non-housing domain where someone might try to apply it :-)