Learned the basics on the wheel in the late 70's in high school but then stopped when school ended. I never lost interest in pottery and always promised myself I would return. Some 32 years later I have set up a small studio and I am once again throwing pots with the intent on selling my work starting in late 2012. I am learning sooo much from videos and wonderful sites like this one.
I will be a part time potter for the next 10 years and then enjoy my early retirement years making and selling my pottery
Bracing with my right hand, I use my middle finger on my left hand to open up to maybe 1 Kg. After that I'll use both my fore and middle finger. Fore, middle and ring finger for 3 - 4 Kg. I have never thought about using my thumbs. I have seen people do it. Should give it a try.