I agree with the concept of using gravity to assist the whole thing, if you've allready been studying that method. The 'lay back on the shoulder' method is also effective when done properly, and I'm sure one may work better than the other for different people. One thing I can say for sure though is thumb position playing is NOT something that should be attempted without a *qualified* teacher, and don't jump in thumbs first and try to play some concerto. Spend some months playing scales, simple etudes, arpegios, stuff like that until you get the hang of it. Otherwise you'll get frustrated, sore, and just plain no fun to be around. :-D