Are you building a Web product? Add the obvious features first.
Let me backpeddle a moment. The most important thing is to get together a first version. Make it have your core features.
Next you may want to add in those pieces from your grand vision. You’ll get there, but I think you should first look for obvious things that are missing. Don’t let yourself regret it later.
TypePad has been out for three years. I have never been a user, but I read what their users write all the time. Often I return to a TypePad blog and want to find a post. Is there really no search in TypePad? That’s an example of an obvious feature. I’m sure the folks at Six Apart (who make TypePad) could even find a search partner willing to give a little revenue share for sending searches their way.
Finding the difference between your core features and frill features is tough. It makes you question how well you understand what your full-grown ideas will look like as embryos.
By contrast, the obvious stuff should be easy. It’s the stuff your gut tells you that you should be doing. If you put it off, make sure you justify it. Then do everything you can to get back to it soon. Your product will be better for it.