Find the image or design of the tattoo you want, either online or in a book. If the image is online you can simply print it out, but if it is in a book, you should take it to a copy machine and print out the image onto flat white paper.
Place the printed paper face up on either your your writing surface and place a blank piece of white paper over it. Tape the two pieces together to prevent any unnecessary motion while tracing.
Trace the outline of the image with your regular pencil. Do not worry about shading or coloring at this point, just create a general outline. Make the pencil stroke light and use your eraser to correct any mistakes or imperfections in your copy.
Peel away the tape and separate the printed image from the one your just traced. Keep the printed image close by -- even though you wont need it for the rest of this procedure, it is good to keep around for a reference and a guide for the artist when tattooing.
Trace over the pencil lines of your copy of the image with a thin black marker. Do not do this until you have finished the pencil copy to your satisfaction.
Flip the paper over and trace the image onto the back with your black marker. If you are using a lighting desk, place a fresh piece over the flipped paper and trace, but if you are using a regular desk, just trace the image onto the back. Achieving this reverse image of your design is absolutely crucial since it is the design's mirror image you will use to make the stencil. Some people use carbon paper, some people just flip and trace, it doesn't matter what you do, so long as you create a reverse image of your design.
Place a piece of stencil paper over the reverse image and tape the papers together.
Trace the marker lines of the reverse image with your tattoo stencil pencil. These lines are difficult to erase, so if you make a mistake, start over with a fresh piece of stencil paper.
Peel away the tape and give the stencil to your artist for application.