Ghosting

Ghosting is a practice technique that helps free the left hand. Pick something to play, such as a scale, easy review song, or passage you are working on. Keep the bow heavy, but only lightly touch the strings with the left hand. The sound will be awful, but this is about the ghostly, light feeling in the hand. Next play the selection again, but sinking barely into the string. I suggest thinking of bending the string, but less than half-way to the fingerboard. The sound will still be terrible. Remember to keep the bow heavy even though the left hand is so light. For the third time you play the selection, sink in more into the string with the left hand, but not all the way to the fingerboard. The sound will be better, but not really clear yet. Then for the final time sink into the string, just to the fingerboard.
This increases your awareness of excess tension in the left hand, and really feels good. It is also a disassociation exercise, since the right arm will stay heavy even as the left is so light. I encountered this exercise through Richard Aaron, who produces such beautiful students. They all play with such ease up and down the fingerboard. Enjoy!