Be on time when meeting your girl. She'll probably always be late, or not ready. We're not ready because we want to look special for you. We've probably tried on 15 different outfits in the last 40 minutes. Also, don't think we didn't give ourselves enough time to prepare, because we have been preparing for hours.
Always tell her she looks nice. Point out something specific like her hair, her nails, new shoes, a shade of lip stick, a piece of jewelry. Let her know you notice the little things. You can prepare for this by.....noticing the little things.
If she lives with her parents, expect to wait around for her to get ready. So be prepared to talk with dad about sports or his car. Tell him the lawn looks great. Again, notice things.
Never cancel with her the day of. She will be disappointed and bummed. She'll think she's not important to you. She likely has been looking forward to being with you. If you do ever cancel a date, you better have a small "I'm sorry" gift for her next time you see her. Her favorite chocolate, a box of cracker jacks, know what her favorite candy bar is, something, anything.
I once had a boy show up for a date to my house with a chilli dog. Before we were dating, we had a lot of common friends and would be around each other a bit. While hanging out at a friends pool one day, he had overheard me say I was craving a chilli dog but I had a date later that night and wouldn't dare eat one because of the onions. A few months later he and I had gone on a couple of dates. Third date he cancelled because of a softball makeup game or something. I was a little upset because I was looking forward to it. The next night he shows up at my front door with a chilli dog. I asked what that was for. He said he was sorry for cancelling and "....well, I know you like them." I'm thinking, well I kind of like them, but how does he know that. And then he pulled a plastic knife out of his back pocket, opened it and cut it in half as we sat down on the step of our porch to share it and he said, "We can both have stinky breath the rest of the evening." Then he explained how he knew I liked chilli dogs. It was one of the best starts to a date I ever had, not because of the chilli dog, but because he noticed something about me months before, and remembered it.