Strip, sand and prime your surface as recommended by the instructions on the paint.
Paint the lightest shade on the item with a paint roller or brush and let it dry completely.
Dampen the sponge in water. Dip the sponge into the second shade of paint and then dab off the excess.
Sponge on the second color using a light dabbing motion. Turn the sponge around every few seconds and slightly overlap the applications. Fill in all areas while allowing the first color to show through. Let the second coat dry completely.
Dampen a second sponge in water, then dip it in the third paint. Let the other two colors show through. Let this coat dry completely.
To add the veiny look in marble, drag the liner brush through the last, lightest paint. Place the tip of the brush on the surface and drag the brush in an irregular movement. Let it dry. Apply a clear sealer to protect the surface.