How can I effectively remove stuck pedals from a bicycle?

To effectively remove stuck pedals from a bicycle, first apply penetrating oil to the threads and let it sit for a few hours. Then, use a pedal wrench to turn the pedal in the opposite direction of normal rotation to loosen it. If the pedal is still stuck, use a longer wrench for more leverage or apply heat to the crank arm to expand the metal. Be careful not to strip the threads or damage the pedal or crank arm.