Set up your easel in a space where you don't mind if the walls and floor become covered in paint splatters. Cover the floors or walls around the canvas to shield this space from the worst of the splatter painting activity, but assume that parts of the room will still get spots of paint on them. Wear protective or old clothing during this process, and assume you will get dirty.
Dip your paintbrush into a jar of acrylic paint, or into the acrylic paint on your palette. Apply the paint onto the paintbrush generously. Don't worry if it drips or runs a little.
Stand approximately one or two feet away from the canvas, facing the canvas. Hold the non-bristle end of the paintbrush in one hand.
Pull the bristle end of the paintbrush toward your body, using the other hand.
Let go if the bristle end of the brush and allow that end of the brush to snap forward, toward the canvas. Paint should fly off the brush and onto the canvas. Repeat this step until paint no longer splatters onto the canvas.
Repeat steps two through five until the canvas is well covered with paint. Clean the brush in the jar of water by swirling the brush in the water, then wiping it off on the rag. Repeat with other colors as desired.