Teaching 3D to a range of students (from 13-19) or higher, can be stressful. But it also extremely rewarding. One of the highlights I done, was getting classes of a bunch of 13 year olds sculpting, they thought they were going to hate 3D because of the usual awful standard teaching, however after a week with me they were sculpting their ideas they had for characters inside Mudbox, it was a pretty amazing sight to see and also to infuse them to carry on with 3D down the road.
And also teaching Pixars Renderman was something special too. When the students saw their creations come out with such realistic shading, and they understood they were using something Pixar uses in their movies, and other studios around the world are using Renderman to create the movies we love, the enthusiasm they were left with was pretty amazing.
When starting, for characters the things to focus, and wish I knew where:
1: Anatomy is a must, any creation even if it's not human has some sort of bases on human anatomy, so studying this will be king, even if it means taking classes where you draw, or sculpt with your actual hands. The real life models and study their form will help you loads in the long run. And of course books that give in-depth views of the human muscles are a must have.
2: Like one, reference is king. You can never have too much, have your second monitor full of images that relate to what you want to create. So for instance, humans have that monitor full of model/human anatomy reference. No matter how long you've been doing this, or how little they will always use reference. No one opens up a program with no images, or drawings of what they want to do.
3: Never be afraid to get feedback, no matter how harsh it is. At first this can always seem scary, because we hate getting negative feedback, it's only natural. However it's the only way we learn too. So making accounts on places like here, polycount, ect. And asking for honest feedback will help you more then anything, even if someone rips the model to shreds, because you can go back and change your model based on that feedback, you can only make something better. Not worse.
4: Don't worry about software wars. If you read online forums it's a battle over software, it's like the whole Xbox one vs PS4 thing, seriously no joke. The thing is with modelling, the skills can be moved around easily. They all work the same, yes some software have tools that are better then others, and also lack some. However they all usually work the same. Once you learn the core modelling skills, you'll be able to jump around most programs at ease, once you work out what software calls its tools. For instance I know: Softimage, Max, Maya, MODO, C4D, and I've done some little Lightwave. They all work alike. So find a package you like, master it. You will be able to transfer the skills. However, Max, Maya, and industry standard, with MODO catching up as it's growing up fast.
Theses are getting old now, and what I could find at hand because all my new stuff is under NDA: