The foundation of a successful construction project is based on getting a complete price for a full job...you get that price by taking the time to put a comprehensive bid package together. Period. There are no shortcuts on this one, you just gotta sit down and DO IT.
That said, enjoy the process, think about how great your space will be when this is all done. Imagine all the things you want in that space...can you see them? GOOD, now add them to your Scope of Work!
You can check out My Plans and Scope of Work on the Resources page of this site.