Locate the source of the squeak. Stand inside the garage and turn on the electric motor for opening the garage door, standing clear of any moving parts. Check that nothing is in the way of the garage door tracks.
Spray the moving part with a little light weight oil like WD-40 and try turning on the motor again. The squeak should resolve itself after one or two completions of the door opening and closing as the oil spreads over the metal parts.
Spray each of the moving parts, from the top of the track--including the spring and the cables--down to each joint and hinge along the door, as well as the rollers. Lubricate the parts of the door handle including the locking mechanism and the guide.