you might also want to plan out HOW you will be giving the gift to her. Sometimes its how the gift was given that makes a bigger splash with the girl.

example, if you are giving a pendant necklace, you can put it on a cute teddy bear and give the teddy bear at the end of your dinner date. Of course this means you will need to stash the bear somewhere in advance (in the restaurant, with one of the staff) or in the car (park very near). Excuse yourself (comfort room break) and return with the gift bear.

also, if she already works... you can send flowers to her at her office. That can set up a good mood for her to have when she sees you later at your dinner date.