Quote: use the phrase "I like it a lot, but I don't know if it's THE ONE. I'm going to have to sleep on it."
great advice
Also,
Quote: Definitely try everything on! I had it set in my mind what I wanted and I ended up with something different.
GREAT ADVICE
To further the great advice above - the sales people fit dresses for a living, even if you think you'll hate a dress, put it on - in my experience the ladies were great in the bridal salons.
Other tips:
1. Do your hair - feel like a bride, do yourself up in a quick updo, it makes putting on fancy dresses that much better, and give you a better sense of how you'll look on the big day.
2. Wear full bottom underpants (pref in nude) the ladies at these salons get right in the changeroom with you, be prepared.
3. Wear a strapless bra, and/or be ready to take off you bra and just try them on, this is not a time to be shy... you are a woman on a mission!
4. If you already have shoes bring them with you (I happened to find my shoes before my dress)
5. Don't bring a harem of women with you, bring your mom and a girlfriend or two... too many opinions is not always a great thing.
Have a blast!!!! This is part of the whole wedding experience... and take pics when you can!!