Before you start, add a glaze to your top coat for extra shine. This thins the wash and allows the bottom layer to show through. An additional advantage of mixing glaze to paint is that it also lengthens the drying time of the paint, giving you more time to work.
Apply the paint wash with a bristle brush. The bristle brush shows off the texture and enhances your effect. Work haphazardly. Cover less than you think you will need, as you can go back and blend or add more if you like.
Stop every three to four feet to use a dry bristle to blend the wash as you go. Alternate between applying the wash and blending it. Leave paint marks by not blending too much.
Use your step ladder to reach higher walls and ceilings.
Use a smaller brush to work in corners.