Sprinkle plain talcum powder onto the floor, concentrating on the areas that squeal the most. Cover the powder with a clean cloth, and walk on the floor as much as you can. This helps the talcum powder work its way into the wood. The talcum powder helps to lubricate the areas between the individual pieces of flooring, where many squeaks originate.
Walk across the floor slowly, and listen for squeaking and other unusual sounds. Mark the spots you identify with a Post-It note or similar item. Identify all the parts of the floor that are squeaking or squealing.
Check the tightness of the floorboards in the areas you have identified as squealing the loudest. A squealing sound is often an indication that one or more floorboards has begun to come loose. Fasten any loose floorboards more securely to the subfloor underneath, using screws or adhesive.