Piano, and most of the arts, require lots of at home practice in order to progress. I have some good news for piano parents though, you don't need to know a whole lot about music to help your child. Scheduling practice reminders into your phone, listening to your child's songs, and a little encouragement go along way. Not sure what to say? Here are a few starters. "My favorite part of the song is...", "The first/middle/last part of your song has really improved", "You played that with a steady beat!". It works because children like to please their parents and when mom or dad show appreciation of the songs they are hearing, their child will look forward to practice times.
As for the invitations, I printed them out on colored cover stock to make them attractive. My students quickly reached for their pencils to write names on their invitations and were excited to hand them out. I let each student pick five invitations and had several colors to choose from. After checking in with my students the following week, practice times were up and songs were better played.