Okay I have some great ideas but let me add: Go to youtube.com and watch Michelle Phan's valentines day date video. It's her newest so you can find it easy. It should be very helpful but here ya go:
Clothes:
Pink is great for V day but don't go overboard.
Skinny jeans are great. Do a dark wash tucked into UGG boots or UGG styled boots
Maybe a flowy top in white pink or red
Hair:
Half up half down and wavy! Some people are gonna say wear it all down but DON'T! It can look like to much a ponytail is cute but its a little to casual.
Half up and half down is the perfect mix betwen both.
Okay so I know you didn't ask for this but I really think that it will help you so please read it
Makeup:
For skin go clean and dewy. Just concealer. Foundation can make you look fake. As for blush I would go with a light pink so you can look rosy and fresh!
Lips just a pink shiny gloss.
Eyes you should do an undereye smokey heres how:
1.Dust a peach shadow on your top lids.
2.Line your bottom lids with black liner
3.Put a sparkly black shadow just a little under but not to much or it will look to dark
4.Put two coats of mascara on top lashes only
YOUR FINISHED
I really hope I helped GREAT LUCK with your date I know that your gonna look amazing :)
*Oh and dangly ear rings and a small handbag that matches your outfit would be super cutee good luck again