My favorite method of teaching anything is starting with a problem and explaining different ways to solve the problem. For example, there are many ways to make the same surface. Some methods produce cleaner (few control points) surface than other methods. If you go to Infinite Skills website, you will see tutorials divided into short videos. Random selection of these videos is posted on the internet so that everyone can watch them and guess the quality of the rest. Lynda has the same business model as Autodesk - it rents its products, but it does not sell them. I want to download the tutorials and watch them later; maybe a year later.
It may be good idea to post free sound tracks of your tutorials on the internet, so that your customers know what they are buying before the purchase.