There are several good schools out there. Every taxidermist may tell you a different one. Do your research and call the schools that you are considering and talk to them. Each one is going to be a little different by way of methods and how far into depth they will go. Anyone can teach you to slap a skin on a form and call it a mount and then give you a certificate to say your a taxidermist, but the true art in this craft is knowing animals, their muscling, coloration, expressions, extenuating their positive assets and downplaying their negative and making that come to life in techniques that are learned far after school and after practice through failed and successful projects. Taxidermy school gives you the 'basics' and steps to perform a mount, but the artistry will come with years of practice and constant learning. People like Charlie Smith, Mike at Natures Way, etc.....they are successful not because of what school they went to, but because they study their work and portray that in each mount.
With that said, a school is paramount to begin this craft. Another great way is to 'apprentice' under a good taxi, which is what I did as well both before and after school.
I would highly recommend, but of course its where I went, Montana School of Taxidermy. Its owned and operated by Jeff Welch who has been in the craft for over 35 years and is one of the most successful taxidermy studios in Montana. I chose his school because he really focuses on the finer details of a mount. The school also teaches you complete tanning through several methods, rugging, and habitat construction. This gives, in my opinion, a larger basis to start at as a beginner and more options to cut costs when starting out. Like stated earlier, do lots of research on the schools you are looking at or considering. Best of luck to you! Joel - BRT