This is how: When you draw this simple object KEEP YOUR EYE STEADY ON THE OBJECT AND FOLLOW YOUR EYE MOVEMENT ON THAT OBJECT WITH THE DRAWING MOTION OF YOUR HAND. BOTH SHOULD MOVE IN SYNCHRONOUS (same time) MOTION. If your eye is seeing an oval before you, such as that at the top rim of this glass, place your pencil at a certain point and trace the shape as your eye "walks" the rim of that glass. Hand and Eye working at the same time, in the same gesture. In drawing GESTURE IS EVERYTHING!
Don't keep bobbing your head up and down so that you lose your "place" where you were looking and your place on the paper. Try to keep the paper in your downward peripheral vision while keeping your eyesight on the object. In other words, as your eye moves (fairly slowly) across the outer shape or OUTLINE of the object, your hand will mimic the shape and length of sides or angles by following the path of your sight. This may sound complex but it becomes second nature quickly. It actually makes drawing VERY EASY!