Dittos to what CP said but do realize that there will be a specific tap drill size for every tap and you must use that tap drill size for that tap or your threads will be a failure. When bought in indivudual size packageing each tap will include the proper tap drill. When you buy tap sets often you must look up the proper tap drill size and provide it yourself. When locating the holes suggest you use the GP hole locator as taped holes must be accurate unlike drilled through or self tapping screws in glass filled mounts.

Also purchase a good tap handle, This you must have to accurately tap the hole by feel. Don,t attempt to use any other type tool. When performing the tap do not just continue to screw in but keep backing off a turn for every quarter turn you turn in. In this way the shavings are cleanly delivered to the flutes of the tap.

Also you can consider the glass filled nylon mounts and use the sheet metal screws that you drill a specific tap drill size and the screw does their own tapping. These work very well indeed and are easier to do.

John