Spot-clean any soiled areas on the house before starting to paint. According to the Western Red Cedar Lumber Association, pressure-washing should be avoided because it damages the cedar and prevents paint from adhering. Instead, wash moldy spots with a diluted bleach solution, and allow it to dry thoroughly. Use a bucket and a vinyl scrub brush. Brush off any other debris.
Cover the windows with a plastic sheet or cardboard, and secure it in place using painter's tape.
Apply a stain-blocking alkyd primer to the cedar using a wide-bristled paintbrush. Paint from side to side, working the paint into the textured wood and around the edges of each board. This type of primer will keep the stain from bleeding through and affecting the paint. Allow it to dry according to the package instructions or at least 24 hours. Apply a second coat for best results.
Paint the house with 100-percent acrylic latex paint. According to the Western Red Cedar Lumber Association, this is the most durable paint for this type of job. Apply the paint in the same manner as you did the primer by using a wide-bristled paintbrush. Allow it to cure, and apply a second coat. The extra coats protect the cedar and ensure the paint lasts.