couple of things that may not have been mentioned, i didnt read everyone's posts. I have to interview at law firms all the time and these are just some small things that emplyers notice, presentation-wise.
1- shoes matter- theyre one of the smaller details that people look at, in fact I had one guy tell me you can tell a lot about a person just based on them, if you dont have a pricey pair, just make sure theyre well shined and no scuff marks
2-small things like clean nails and fresh breath do make a difference, take some mints with you
3-brevity is appreciated, emplyers dont like people who ramble on
Hope this helps