well from my own experience (of 2 dates with the same girl) i would advice clichÊ:
i'm assuming you're a guyu:
-Be polited, but don't be insecure, you don't have to like everything she likes, you have to be kind, gentle and try to have fun with her , not for her...
-try to be a good listener - SA people then to think they are good listeners just because they are quiet, that's not truth because generally we are so focused on ourselves that we tend to overlook the other person...
look at her, her expression will speak a lot, but don't just assume stuff if the person seems unconfortable you can try to make things better, but assumin you're responsible wont help.
try to talk a little about you, find something in common, ask questions that need an explanation , but don't be too invasive...
-i'm old school, if youre dating a girl you have to pay the bill, i would only share if she insisted very much - even if she turns out to be a horrible person...
-finally try to have fun no matter what, if tour date is not happy chances are its not you fault, if you don't click patience, and if she acts like a idiot that's probably for the best because chances are the person is an idiot
i don't know if this is your first date, but even after reading and preparing alot you will be nervous, there's nothing you can really do about it...
when i first when out on a date, it was visible that i was trambling like a bamboo (and i was 21) , even today i thank the girl for being such an angel with me, if you have any visible indication that youre nervous try to prepare but don't let it keep you from doing so, there are very nice people in the world.
You've got a lot of guts. A date I can just about handle, but a double date? Woah just the thought makes me feel uneasy
i don't know, i kinda like the idea of having a friend around.