shorten stitch length
Try shortening up your stitch length, too. Also, if you can adjust the speed of your machine you may want to dial it back a bit, this can keep you from going too fast.
As has been stated, free motion is definitely a skill set and the more you practice the better it gets. Make yourself a pile of practice sandwiches out of muslin and leftover batting. Sew 1 or 2 of these practice sandwiches daily... you can do this as a warm up activity. You will be amazed at how daily practice can improve your skill.