Taps at the toe should follow the outside contour of the shoe and reach to the inside without going over it. If the tap sticks out beyond the edge of the shoe where the shoe curves, the tap must be filed away so that it matches exactly. USATap notes that some taps come with sharp edges; these must be filed down or sanded with sandpaper until they are dull, as sharp edges can cause injuries or damage dance floors.
Taps on the heel of the shoe should also be aligned to the outside edges of the heel and extend to the inside edge without hanging over. As with toe taps, any part of the tap that extends beyond the heel should be filed away, and sharp edges need to be filed smooth.
Always use screws to put taps onto shoes, never nails. Taps should be tight on the shoe, never loose or "tuned" or "jingle." Make sure that the screws do not stick out from the taps, but are sunken into the holes in the taps so that they do not gouge dance floors or cause you to trip.