Use a marker to draw an arrow shape around the bottom of the cushion.

The arrow's point should fall toward the center of the cushion.

The points on the sides of the arrow should extend well beyond the edge of the cushion. They should not be aligned with the corners of the cushion.

This is done to ensure that there will be enough fabric to sufficiently cover the cushion.

The bottom of the arrow should line up with the sides and bottom of the cushion.

Repeat this step to draw a wider arrow for the side of the cushion.