I went to school to learn the basics then learned advanced techniques from more experienced taxis. Here are a few things............
www.taxidermy.net - great website for learning
Taxidermy Today - magazine for taxis
Breakthrough - another great mag
Your state association is set up for helping people learn.
Call 1800-279-7985 for McKenzies Taxidemry Supply and have them send a catalog. They will have videos and supplies. Find out if there are any taxis near you that would let you sit in and watch. If you live in NC, come by and sit here.