If your stove knobs' markings have faded, you could make etchings with a sharp instrument, or use nail polish or a paint marker pen, to make new markings. However, even if you have a steady hand, the result may be less than ideal. For a truly polished look, and one that will last, use dry transfer lettering from your favorite craft or hobby store.
Refer to the owner's manual of your stove to remove the knobs. In most cases, you should be able to pop them off by pulling them toward you. If they're stuck -- perhaps by a buildup of grease -- you may need a pair of pliers to pry them loose.
Trace the circumference of one knob on a piece of paper. You will use this is a template to mark where your stove ignites a flame and then where the flame turns to low, medium and high.
Remove any trace of the original knob markings with a piece of steel wool. Place the knobs in a bowl of white vinegar. Let them soak while you make the markings on your paper template.
Cut out the paper template and wrap it around or hold it against the frame of the knob -- meaning where the knob used to be. With a pencil, make a line where the flame ignites and also where the flame turns to low, medium and high. Check your work against each burner. If the markings don't line up on each burner, make separate paper templates.
Remove the knobs from the white vinegar and wipe them dry. Clean the front of your stove, if you wish, before reattaching the knobs.
Use the marked paper knob template to place a dry transfer letter on the knob for each of the four markings: "F" for flame, "L" for low, "M" for medium and "H" for high. Rub the letters, one at a time, onto the knob using your forefinger. Raise the transfer sheet slightly to ensure the letter has indeed transferred. If not, apply greater force or use a credit card or the back side of a spoon to make the transfer. Reattach the knobs to your stove.