I have been playing for a few years now. I am just finishing up the Suzuki book #1. I find getting up on the "G" string is difficult. My left hand will cramp up. I know one of my issues is that i am grabbing with my thumb. My other issue is that i am trying to stretch out my left fore arm because i can not rotate it around enough to reach the "G" string. would anyone have some advise for me on these issues? How can i correct this?