If your dryer is making a lot of noise here are some simple tips on what you can check. If this doesn't fix it, a more in-depth look might be necessary.
Loud rattling or humming: A loud vibrational noise might be something as simple as the dryer's leveling legs not having a good solid contact with the ground. If the body of the dryer is slightly twisted because one of the legs is higher than the other then the chassis or some of the metal panels might be vibrating along with the motor, amplifying the noise. Check to make sure the dryer is level and that the legs make a good solid contact with the floor.
Screeching: If a dryer is squeaking or screeching then the usual suspect is the tensioner / idler pulley. This is a normal maintenance part and fairly easy to replace. Once the pulley starts to make noise it is best to replace it. Remember: A spray lube like WD might actually make things worse after just a few days.
Thumping noise: This usually means that the drum support rollers are seizing up or that the glides are nearly gone. These are normal maintenance parts and are best replaced when they signal signs of wear or seizing.