To prepare a canvas for painting, start by ensuring it's free of dust and debris. Apply a primer or gesso to create a smooth, non-porous surface. Use a wide, flat brush to apply an even coat, and let it dry. Lightly sand the canvas, and apply a second layer of gesso if needed for a smoother finish. For oil paints, ensure the primer or gesso is completely dry before painting. For acrylic paints, a single, even layer is often sufficient. This process creates an ideal surface for painting, allowing the colors to adhere and the artwork to come to life.