Doing my first bridal session, need tips?

I'm not a professional photographer by any means, but would love to become better at it and make it a side job apart from being a sahm!
Anyways, I'm doing my cousins bridal portraits next weekend (2 weeks before the wedding), just would love any tips on shooting the protraits. I have a nikon D3000, 55-200mm and 18-55mm lens. We're taking photos outside at biotanical gardens here in TX. I'm so afraid of sitting her down in her dress.

tips: Iso, settings, etc.

Okay, she has to be in THE dress, made up as if for the wedding, and everything tailored and perfect. None of this "Oh I'll have my hair done on my wedding day, but for now I'll just pull it up with a plastic clip" nonsense. The First Rule of Photography is "Get It On The Negative," now digital, but the point is that it has to be PERFECT before you take a picture of it, got it?

Next: the botanical garden is a good idea, but don't think that just because you're in the botanical garden that you've picked a good background. FIND THE BACKGROUND(S) FIRST! Then put your subject in front of it and shoot the shot. Sometimes it might surprise you. The best background I had at one particular "botanical gardenny" wedding place was right next to the dumpsters. It can happen.

Shoot your sitting either in the early-early morning, or late afternoon. That way the sun will be at a nice low angle, and your lighting won't be so flat and contrasty. Bring along a flash to fill in if need be, or reflectors if you have them. Good reflectors can be had from foil board, which you can get at a major national chain hobby store frame department. Have an assistant (you will have one of those, along with a stylist who can keep the bride's hair, dress, and makeup freshened) hold the reflector "downwind" of the bride, and aim the reflection back into the shadows. It's like an almost-free light.

Make sure to carry a fog filter with you, or a slice from an old pair of black stockings, or a sheet of glass you've either smeared with petroleum jelly or sprayed with hair spray. It makes a great "romance" filter.

Live up north and it's cold now? Wait until spring. There's NO substitute for perfection, and brides are NOT perfect if they're freezing, UNLESS she had sense enough to choose something like a fur-trimmed wedding dress, preferably with a hooded cape.

Study the pictures in the "bridal bible" magazines for ideas, and either buy the magazine, or sketch the pose and setup in your notebook (can't draw? LEARN!). Imitate until you are confident you've got it.