Here's what I know...
(1) Plan to act surprised and excited; "act" being the operative word. Even if you know where you are going tonight because you snooped in his blackberry, feign surprise when you arrive there. And even if you have been to his restaurant choice 15 other times, pretend to be excited when you get there; after all this is the first time you are going there with him. He will be crestfallen if you act any other way.
(2) Keep how many cute gifts you schlep to the restaurant to a minimum. No sense looking like a tourist for christ sake. Plus keep in mind that it's only V-Day not his first Christmas!
(3) Dress sexy tonight; it is a dress or a skirt night, girls! Even if it snows, don that sexy dress, and let him see that you are putting forth the effort.
(4) Wear sexy lingerie or at very least matching bra and panties. You are going to get action tonight and just like you wouldn't want to end up joining the mile high club with unshaven legs, the same applies to lingerie of V-Day!
(5) You need to be prepared to "eww and ahhh" about his attempt at romance, no matter what. If you don't, he will never try again and certainly some effort is better than no effort!!
(6) Plan on being frisky. V-Day is the best foreplay so keep in mind that tonight is not the night to have a headache, skimp on the BJ or have to check on the kids.