Drawing a simple design on paper without lifting the pencil is most helpful. Repeat. Repeat. Repeat. After you have drawn the simple design and feel you can do it (it does not have to be perfect--you are looking for smoothness), now take your well basted practice piece to the machine. Without engaging the needle or motor, move the fabric under your darning foot, just like you would if your foot were on the pedal. Repeat until the motion feels natural. When ready, engage. Remember to breathe.