Interview in person. Meet and get bids from at least two (but no more than four) florists. Otherwise, you'll be counting stephanotis in your sleep.
Review their work. Flip through each florist's portfolio, and ask yourself what you like or dislike. Does the work reflect different styles, or does each wedding look mind-numbingly the same? Is there anything there that you'd like at your own wedding?
Size up their personalities. Since you'll be working closely with the person you ultimately choose, ask yourself this: Did you like the florist personally? You want to select someone who meshes well with you in addition to having talent. The best florist in town isn't worth hiring if you felt he didn't spend enough time with you, wasn't a good listener, and dismissed your ideas.
Consider their willingness to work with you. The ideal florist will have creative ideas that appeal to your sensibility, taking into account your tastes and style. He should be forthcoming on how to get the most for your budget with less pricey blooms, and which flowers will be in season.
Research their reputations. Has the florist gotten good press, or -- even better -- word of mouth? How about references?
