It is traditional for the bride and groom to cut the first slice of cake together.  This is said to ensure future happiness and a willingness to share their lives together.
To decide what style of cake you like, look at the magazines. When you meet with your cake decorator take these pictures with you and have an idea on how much your budget is.  Many bakeries have a large selection of cakes for you to view.  Provide the cake decorator with colour swatches of your dress and bridesmaids dresses, if possible.  The top of the cake is traditionally saved for the first anniversary.