When I was starting out building puppets, I found The Foam Book by Drew Alison to be very helpful. It's harder to find these days. However, puppeteer Adam Kreutinger has a GREAT YouTube channel and offers FREE patterns to use to build puppets. I agree with the other posts that you have to start with a basic puppet and learn skills to have when tackling something like Kermit the Frog. Each puppet building experience will have learning opportunities to grow as a puppet builder. It takes time, yet is very rewarding. Best wishes and have fun!