The Brassy Apple has a good tutorial if you want to cut out your own letters. http://brassyapple.blogspot.com/2010/08/cut-it-out-canvas-tutorial.html
However, I am not likely to cut out my own letters so I am trying another route. Here are my modified instructions:
#1. Purchase a canvas (at your local craft supply store) and paint your canvas the color you want your letters to be. You can also cover it with fabric if you choose. If you want them white, you can skip this step!
#2. Purchase stickers in the various fonts you want to use to letter your canvas.
#3. Cut stickers into individual letter and lay out your saying, quite, or name before you actually put the stickers onto the canvas. This will allow you to tweak the design. You can add stickers in various shapes or just use painters tape for block letters or shapes.
#4. Place the stickers on your canvas.
#5. Paint the entire canvas, including over your stickers. You can paint on solid color or get creative here. Let the kids paint all over the canvas or stripe or block paint it.
#6. Let the paint dry for 10-20 minutes then peel off the stickers.
#7. Let the paint dry for 2-24 hours then spray a clear protective coat over the project.
Enjoy your painted canvas!