Determine the approximate size of the tattoo and designate a portion of the blank white paper for the design.
Sketch the outline of the design with your regular pencil. Use light strokes, as you might make mistakes that you will need to completely erase. Don't worry about shading or incorporating colors -- just draw the rough outline.
Trace over the rough pencil outline with your thin black marker. Be sure every line is exactly how you want it before you begin this step -- once you start tracing in black you will need to start from scratch, if you find an uncorrected mistake. Again, do not shade or color.
Flip the paper over and copy the black lines onto the reverse side of the page. This is necessary, since it will be this reverse image that is stenciled so it will lay frontwards on your skin. Do this in a well-lit area to ensure the lines show through. If you don't have a tracing desk, a normal desk under a bright lamp will suffice.
Tape a portion of stencil paper over the reverse image of the design so the papers will not slide apart when tracing. Unnecessary motion can cause mistakes and you might need to start over with a fresh piece of stencil paper.
Trace the image onto the stencil paper using a tattoo stencil pencil. Be conservative with the amount of pressure you use, as this paper can rip easily, but each line should be clear and pronounced.
Give the stencil to your tattoo artist and allow him to make subtle corrections or alterations as the artist will always know best how a stencil should look before application.
Allow the artist to shave the area to be tattooed and to wipe it down with a stencil solution or glycerin-based deodorant to help the stencil ink stick to your skin.
Hold the ink side of the stencil against your skin and press firmly for at least 10 seconds before removing. If the image did not transfer completely (or to the artists liking), the ink should wiped off with alcohol and a brand new stencil may be necessary.