Make sure that you don’t overload them! Keep you lint trap clean after every use and once every six months use a dryer vent brush to clean the inside of the vent.
Don’t set anything on top of your dryer (laundry detergent, liquids, clothes baskets, etc.). Too heavy loads can cause the top to cave in causing the drum not to roll properly. Spills can cause an electrical short and maybe a fire if not taken care of properly. It is always a safe bet not to set anything on top of them. Dryers were not made as shelves for storage.
Always check your exterior dryer vent for lint build up inside. Over 60% of houser hold fires are caused by lint build up inside the dryers. If you suspect your dryer is not heating properly then this is the first thing to check before call a technician. If a dryer gets too hot then tit may be a venting problem and not the dryer itself. If the problem still persists afterwards the call a professional.