Move the furniture out of the room. Cover the entire floor with drop cloths. Tape plastic over windows, doorways and adjacent walls you don't want painted.
Mix equal parts of clear acrylic glaze, acrylic paint and water in the bucket. Use separate buckets for each color.
Dip the toothbrush into the bucket of paint and shake a little of the excess paint from the bristles to prevent big globs from spraying onto the wall.
Stand about a foot away from the wall and drag your fingers across the bristles while aiming the toothbrush at the wall. As you drag your fingers, sweep the toothbrush through the air parallel to the wall surface to cover the wall with splatters. Aim for a random application and continue filling the wall with a light or a heavy application of splatters.
Switch to the scrub brush if you want a heavier splatter effect. Dip the scrub brush into the bucket and drag a wooden craft stick across the brush bristles to deliver heavier splatters to the wall.
Apply one color of splatters to the entire wall, working in 3-foot sections, to create the coverage you desire.
Blot splatters with a sea foam sponge if they become too heavy. Press the sponge lightly against the splatters and raise it straight off the wall once or twice in the same spot. The sponge softens the splatters slightly by lifting away some of the paint and blending the color.
Switch to a different paint color, using a different toothbrush or scrub brush in another paint bucket. Apply additional splatters over the first color to make multi-colored splatters on the wall. Make the splatters as heavy or light as you desire. Try splattering the first color over the wall with the scrub brush and add one or two different colors over the wall with the toothbrush for a lighter effect.
Step back and assess the splatters on the wall. Add more if you want a heavier look.