Both flowers and decor are two key elements of your wedding.  It' represents the theme of your wedding and sets the mood.  Make sure that you choose flowers and decor which fits your venue, theme and color scheme.  Keep in mind that not all flowers are available during the year.  If you choose a type of flower which is not in bloom at that moment or available it means you will need to import your flowers which is going to be expensive.  Get different quotations from different florists, ask the venue if they can refer you to a florist that they've worked with before.  Make lists of all the places you will need flowers, for example at the ceremony, at the reception, your bouquets ect.