I would also agree to work on your movement. Try to time your split step at the same time as when the person on the other side of the net will hit the shuttle. Try to bend your knees so that your stance is lower on the split step (pretend that it is a squat). Then regular four corner movement patterns with lunges to the front of the court. If you can get to the shuttle more easily, it will be a good foundation to hit better shots.