Contest and Zazzle Store Suggestions Requested

I’ve been inspired.  Cake Wrecks, that bastion of baked badness, recently opened a Zazzle Store featuring some gags based on their hilarious cakes gone wrong photos.  When I saw that, a lightbulb went off over my head.  I had just taken a bunch of great photos from Charleston and I had a few others I’ve taken over the years.  I had thought once or twice of selling prints, but never really got serious about it.  Zazzle could change that, though.  I could upload a photo, add a witty caption, and instantly be able to sell posters, prints, shirts, etc.

I’m awful at coming up with witty slogans, but I figured I could run a contest.  I’ve never really run a contest or a Zazzle store, before though.  So before I dive in, I’d like to get as much advice as possible.  What suggestions would you have for someone who’s about to run his first contest and his first Zazzle Store?