Pick a design carefully; one that doesn't have too many details or bridges is best for a beginner. A bridge is a narrow section that connects parts of the stencil and helps create the individual elements of the design, such as a grapevine stem and a bunch of grapes.
Browse through a magazine and find a simple picture that does not contain many narrow bridges and tear out the page. Look for a black and white picture or one that does not have a lot of color variations in it. This makes it simpler to cut out the stencil. Another alternative is to print out a free stencil template online.
Lay the design down on your piece of plywood or another type of sturdy background. Use something that you don't mind damaging with a utility knife. Try to use a small piece of plywood that you can rotate as you cut out the stencil. This prevents your wrist and hand from tiring quickly.
Attach the picture to the plywood by taping it at the corners with masking tape.
Place the plastic sheet cover or acetate over the design. Tape it in the corners as well. This prevents it from shifting while you are cutting.
Position the utility knife blade on the plastic sheet and bring the blade toward you as you cut out the openings of the stencil.
Rotate the plywood if necessary to cut the plastic sheet in a more comfortable position until the stencil is complete.
Remove the tape and pop out the areas where the paint goes on the stencil with your fingers. These are called islands.