Start by fixing your start. Use the same set up procedure as for the deadlift. Set your stance, then grip, then shin/knee position one at a time and without moving the bar. The bar should always be over midfoot and your ass should be in the same nice, efficient place (higher than you think) every time. You're rushing and it's sloppy.
Set up is harder to do when the weight is silly-light. Focus. Add some weight.