Answer: You have to use their name! And play with it. Make it rhyme or find other complimentary words that start with the same sound.
Is her name...
Cindy: Sweet Cindy Loo
Ariel: Adorable Ariel-a-pie
Rachel: Rachel Pretty Eyes
Is his name...
Dave: Darling Dave (or Davey, if you think he can handle that)
Edward: Mr. Edwonderful
Pete: Sweet Pete
Matt: Magnificent Matt