Sketch in a circle for the sphere or ball shape, drawing lightly.

Sketch in an ellipse at the base of the circle for the shadow.

Determine where your light source is coming from. Leave a white white highlight where light is hitting the sphere or ball.

Shade in the darkest areas first. Use short strokes that follow the counter of the circle.

Work from the outside of the circle in toward the highlight. Use lighter and lighter shading as you get closer to the highlight.

Go over all the shaded area again making the dark areas darker. Try to get an even tone as you transition from darks to lights.

Leave an area on the bottom darker part of the sphere just a bit lighter than the surrounding dark values. This is the reflected highlight. Light is hitting the table (or surface) and bouncing back onto the sphere leaving it a little lighter.

Darken the core shadows of the sphere even more.

Lastly, darken in the ellipse to make the shadow. Shade in more lightly at edges of the shadow to soften it a little bit.