Do you have any friends you can con into volunteering with you? Having someone you know nearby might make it feel a little more comfortable for you; that's what I do (took a cooking class AFTER I got my girlfriend to sign up with me).

Do you have the stencils or can you get some like them? Go to the grocery store and buy 3-4 various melons or squash and "practice". It could be hilarious and you can eat the melon afterwards and use the squash for decoration for a bit then "abandon" it in a park quickly in a few weeks for the squirrels to eat, LOL.