How do I move a multisite back one level in the directory? (from the sandbox to the root)

I am working on a redesign of a site and I’m using a multisite structure. I am building the site in http://www.site.com/new/. When I’m done, it should obviously be on display just at http://www.site.com. I don’t want to go to all the trouble of building this, then try to move it and mess something up with the database then end up just building it all again from scratch at the root (this happened to me last time I tried to move a multisite). What pointers can you give me, do’s and do not’s, that you’ve learned from moving a multisite?

I appreciate the advice. Thanks