The concept is simple. Bringing your product to market is the single most important feature you can put on your product roadmap. So when you start thinking about adding this and making that super cool, stop yourself. Remember you are just delaying your launch and giving the competition the opportunity to get ahead of you.
Nothing is perfect in the first iteration. Get to market, solicit feedback, and improve along the way. It is so simple, I have boiled it down to the following haiku:
You are not Facebook
Your competitors are fast
Launch it; get feedback
Every feature you add delays your most important feature - launching.