Slide the dryer several inches farther away from the wall and from the washer as well. This helps prevent vibration-related collisions that result in squeaking.
Place a rubber mat underneath the dryer. This absorbs vibrations that lead to squeaking.
Listen to the dryer while it's running to gauge where the squeaking is coming from. Unplug the dryer and spray lubricant into the joints and areas that are squeaking to help minimize the friction that causes the squeaking. With the dryer still unplugged, open the access panel in the back with a screwdriver to reach additional dryer components for lubrication as needed.