One of the easiest ways to do this is with promotional products such as specifiers and wristbands. Everyone loves a great deal, and they'll love a custom specifier as much as you love their cupcake business! (Just make sure they're edible!)
Create Your Own Music Playing: If music is your bag, you can easily create custom playlists for your patrons. If you have the opportunity to test a song, why not give it a shot? Maybe it's the perfect instrumental for the occasion, or perhaps you know the exact words to a popular song. Either way, giving your guests a song to sing along to can really make their experience more enjoyable. Just be careful not to overdo it!