A common goal doesn't hurt either. It's not so much of a necessity as the proper etiquette aspects, but it doesn't hurt to have something to lighten the tension and make things more casual. That's pretty much how I landed my job... well, that and the fact that the fates must've been working in my favor. But it'll make you seem like a friend as well as a coworker which isn't bad. What friend wouldn't get another friend a job if able to? Face them and make plenty of eye contact with everyone in the room while speaking and give your undivided attention to whomever may be speaking as well. And when someone asks you if you have any questions ask a question, it'll make you seem more interested in what they do. And in the occurance of a hand shake, don't just flop a cold, dead fish type hand shake in there, make it firm and respectable. If you're going to go limp then you may as well just greet them with a kick in the crotch. It'll make you look just as good. Of course these suggestions are more so just things to polish up the rest of your act with, if the interview itself doesn't go over too well then the chances are people aren't going to be saying "but he gives great hand shakes". Brush up on your charisma, do a google search for questions typically asked in an interview, gather up all of your self-confidence and knock 'em flat.
The Gods Made Heavy Metal, And They Saw That It Was Good
They Said To Play It Louder Than Hell, We Promised That We Would
Hulk Smash!!
Whatever you do, don't eat limes. A friend of mine ate a lime once and BAM!! Two years later. Herpes.