There's a couple of books that stood out as being helpful here, both from Mike Cohn, an active member of the Scrum community.
|Mike Cohn's Agile Estimating and Planning|
is a primer on putting together a project plan using estimating techniques such as user stories to assemble it.
|Mike Cohn's User Stories Applied is my other recommendation. It talks in depth on what a quality story will look like, what questions need to be answered at what level of detail, and how to arrive at a good estimate. One of the more interesting subjects for me was the "Epic Story", which is a very large story with a very rough level of detail, that is a placeholder for a feature set that will not be implemented in the immediate future.|