How do you fix squeaky floors in a home?

Depends on what you think is causing it.You could try spreading chalk powder with a broom,so the powder gets in between the joints of the boards.Talcum powder is ok but a bit perfumy,ballroom powder is easy to get and doesnt smell.If your sub-floor is timber,it could be caused by insufficient nailng of nogs between joists.If floor is on ground level,you may be able to access sub-floor from under house.