A - Have a basic idea of the essentials... such as how much you can afford and about how many guests will be attending. It also helps to have an idea of your colour scheme. Look through magazines or books to start to form your ideas. Will your cake be traditional, modern, or something different, like cupcakes?
B - Form a first impression of the baker through recommendations, viewing the web, or past experiences at the bakery. You may also wish to check with the Better Business Bureau before proceeding. Check the availability.
C - Check out about 3 bakeries to find the one that best suits you. Make an appointment for a consultation and tasting, to make sure the cake both looks and tastes good.
Discuss the style, size, flavour, fillings, type and colours of icing, and the topper. If you wish flowers on top, that will have to be discussed with your florist. Remember that the time of year and the level of formality of your wedding will affect your choice of cake.
D - Sign the contract. Make sure it includes the details (style, size, flavour, fillings, icing, topper...) the final cost (including taxes, and delivery, renting of accessories/designated cooler if any are applicable.) The cancellation policy and back-up plan that should be in writing. Make sure the amount of the deposit and when it is to be paid is clear, as well as how much is owing, and when.
Suggestion: Supply your baker with colour swatches, if possible. You may also like to supply appropriate ribbon to be tied on the knife and server.