Make sure the lock is in the neutral position
Do not force the broken key deeper into the lock
Apply a small amount of lubricant to the keyway if needed
Use needle-nose pliers if any part of the key is sticking out
Use a broken key extractor if the fragment is flush with the lock
Slide a thin jigsaw blade or saw blade with the teeth facing out alongside the key fragment
Hook the key fragment and pull it straight out
Use a strong magnet only if the key is magnetic
Tap the lock lightly to help the fragment shift position
If the fragment will not move, remove the lock cylinder if possible
Take the lock to a locksmith if extraction fails
Replace the key after removal and test the lock gently