Flip over the pair of heels and measure the height of the heel tip. You can find a chart of corresponding replacement heel tip sizes online. Based on the shape and size of the heel tip, buy replacement heel tips at online retailers, cobbler shops or in the shoe department at most supermarket stores. If you cannot figure out the exact size of your heel tip, most brands of replacements should be able to fit one size up or down.
Using a pair of pliers, remove the old heel tips by lightly twisting and wriggling until the old heel tips pop out.
Sand down the shoe with sandpaper if the heel is uneven or holds remnants of glue or other material. Once the old tip is out, align the nail of the new tip with the hole on your shoe.
Use a hammer to push the new tip into place by using a light tapping action. Once the tip is fully secure, repeat the process with the other shoe.