Materials: a bandana, a shoestring, and three safety pins. The 3/4" ones (19mm) work well
Step 1: Fold the bandana twice so it forms a smaller square, and lay it on a surface.
Step 2: Lay a string across the bandana, fold the top of the bandana over the string, and safety pin the fold in place (the safety pin is not centered, it's off to the right a little bit). Note that the safety pin "traps" the string.
Step 3: Grab the sides of the bandana at the middles, and pull the middle of the bandana up so it's even with the top.
Step 4: Fold the bandana so that the bottom is even with the top. (If you were to look at the side of the bandana now, it would take on a "W" shape, like an accordion fold.)
Step 5: On each side of the bandana, near where the string protrudes, safety pin the various folds together.
Step 6: Strap it to your ugly mug and venture out into the world.