My wedding cake ideas are focused on the cakes with fresh flower designs. (With you as the floral designer having the job of traveling to the reception hall with all your supplies in order to decorate the cake after it has been delivered).
Always contact the cake baker and find out what time the cake is being delivered. Many professional cake makers are willing to add the flowers to the cake themselves if you drop them off at the bakery shop. This saves a lot of time on the wedding day!
If you are the one adding the fresh flowers, you must always be conscious that the cake not only LOOKS pretty - but that you must take precautions that any decorations on or inserted into the cake must be safe to consume. It is wise to take the time a care to prepare your flower stems ahead of time.
I always break open a new roll of corsage tape instead of using one that has been lying on a dirty design table. Buy yourself a brand new box of toothpicks (the solid round, not the ones that break easily). Cut your flowers short, taking care to seal off the open end of the flower stem with tape. Then insert the toothpick into the bottom, puncturing the corsage tape. If you wish, cut wax paper or parchment paper into small squares and use one of the toothpicks to puncture a small hole in the center of each square of paper. Slide these papers up the toothpick so that it covers the bottom of the flower and protects the surface icing of the cake.
Remember when adding other decorating elements (such as crystals, diamond wrap or other non-edible decorations) you must treat them the same way. Take the time to wash all your various decorations (don't forget the scissors and other tools!) Be prepared and have all this done ahead of time. It will save you time and allow you to get in, decorate the cake and be out (usually under 20 minutes) I usually lay all my flowers and other decorations in a clean cake pan to transport to the reception venue.
This may seem like a lot of trouble, but professional florists have to take care that no one eating the cake has a bad reaction resulting from the flowers on the cake.