Measure the area that is to be tattooed or just hold a piece of paper against the area and eyeball approximately how large the design should be.
Sketch your design with a regular pencil and use your eraser to correct any mistakes. Don't worry about shading or color at this point; just make a general outline of the design, but make sure every line is perfect before moving on to Step 3.
Trace over the pencil lines with a black marker. The thinner the marker, the better, as the line can always be made thicker but can't always be reduced. Erase all pencil lines once you've completed the trace in black marker.
Flip the paper over and place over a lighting desk or well-lit drawing surface so the lines show through to the other side. Trace the image onto the back of the paper with your black marker, or do it first in pencil and then in marker if you want to be even more cautious. Achieving this reverse image will be vital to creating the stencil, which must be backward in order for the tattoo to be frontward.
Tape a piece of stencil paper over the reverse image once you've completed it.
Trace the reverse image onto the stencil paper with a tattoo stencil pencil. These lines will not erase easily, so if you make a mistake, it is advised you start over.
Remove the tape and give the stencil to your tattoo artist for application.