Identify the exact spot where the squeak occurs
Walk on the floor to locate loose boards or joists
Sprinkle talcum powder or powdered graphite into small gaps between boards
Drive finish nails into loose floorboards and set the heads below the surface
Use wood screws to secure loose subflooring to the joists
Apply construction adhesive between the subfloor and joists if accessible
Install a squeak repair kit from below if there is basement or crawlspace access
Shim gaps between joists and subfloor from underneath
Reinforce weak joists with blocking or sistering if needed
Replace damaged or warped boards
Sand or refinish the floor after repairs if necessary