Ask for recomendations from other vendors, venues, and brides.
Check out WeddingWire and the Knot sites for ideas.
Don't forget to look for a florists facebook and Pinterest pages.
Try and choose your florist up to 12 months in advance of your wedding date. Most brides book within 6-8 months.
For the 1st meeting, bring any pictures you have collected on pinterest or facebook, from magazines or any other media.
Bring color swatches or pictures of the bridesmaids dresses, and a picture of your bridal gown if possible.
Be sure to bring any "save the date" or other printed material you've ordered.
All of these tips will help your vendor plan your special day.