Just dont over prepare. Be prepared, but to the extent that you just have a framework to work off in regard to what questions you're asked. That way, the thinking on your feet you're forced to do, even if it doesnt make you feel comfortable, probably makes you come across as quite confident in that what you say will probably be more fluid and conversational in manner than a rigid pre-thought answer. You always mess up pre thought answers too I reckon.
Handshake wise, be firm and look them in the eye (EDIT: ha, I meant eyes, unless theyre a cyclops!), but dont grap it with the intention of making them grimace and dropping to their knees.
Straight back without looking like your holding in a turd is pretty essential too. Wont go over the other advice people had posted, since most people have pretty useful advice here.
I think the key is to think of it as a game or an opportunity to show how much of a legend you are. You've got to have more substance than style (unless your a master bull****ter) but you still need a bit of style.
What type of job is it?