IMHO, McCain & Palin ought to be preparing as if Obama & Biden were highly polished debaters . . . they need to work their buns off in preparation as if they were the underdogs.
Hopefully, they have a good "opposition research" staff and can come up with a few actors (?) to fill the shoes of their opponents during rehearsals.
Especially for the debate on NBC where Tom Brokaw is the moderator . . . they need to assume he's going to push the NBC line and be an advocate for the Democrats. (Actually, in order to agree to an NBC-hosted debate, they should have insisted on a FOX debate to provide balance.)