It takes practice, practice, and more practice. Before I start quilting(free motion), I always make a potholder(9x9 sandwich), it warms me up and gets my muscles coordinating again. Also go to daystyledesigns.com this lady is a wealth of info. But, I think, the problem with your tension is probably the top tension not bottom, or it's your speed. You have to learn to coordinate your foot speed with you hand(fabric) speed. But, keep trying, all of a sudden you will notice you're doing it without struggling. It does become fun.