You can preserve your wedding bouquet by first talking with your florist before your wedding. Let them know that you wish to preserve your wedding bouquet. They can then make suggestions about incorporating flowers that dry well.
Silks are also an alternative.
Your florist may provide a freeze dry process or offer to preserve your bouquet for you, know your alternatives and discuss with them their suggested method. If you have fresh flowers, start preserving your bouquet at the reception. Put the bouquet in a place as to not be disturbed. You may request a floral box to help in this matter. Before leaving on your honeymoon, you or a person you appoint can start the preservation process.