Check the bolts on the bike are tight. The consequences of a stem bolt worked loose do no bear thinking about. That irritating creak from the saddle could be cured with a quick twist of an Allen key.
Many have a torque setting, which should be adhered to: over tightening the seat clamp on a carbon frame, for example, can cause damage. Typically, the torque rating for these bolts is 5nm or 6nm.