I agree with everyone above but also add that given that you may over
estimate what you can deliver, make certain that you prioritize the
functionality. I have just finished the Analysis Phase of a 14 month
software project and we have already decided to cut scope (move to
phase 2) because of risks that were uncovered. Because we strategized
and completed our technical analysis with components in mind, pushing a
chunk of functionality to phase 2, based on priority, was not a huge
issue.
Simon
http://www.simonmetz.com/project_management/