Your helmet is very important. It will be the only protection between your head and the ground in case of an accident. You need to take care of your helmet and your goggles and make sure that you keep them in top working order.
Helmets age. No matter how good or well made, even the best helmets age due to the plastics, resins, and foams that are the make up the interior of the helmet. Don't hang your helmet off your ATV or motocross bike. This can stretch your chin strap and make your helmet not fit at well, and an ill-fitting helmet isn't safe.
Gasoline can break down resins if your helmet is exposed to it on a daily basis. If you store your helmet in a garage, be sure it is not near a can of gasoline.
Also, helmets are good for one impact only - inspect your helmet for small and tiny fractures in the surface. This would indicate that your helmet has been used in an accident or dropped from a significant height. In either case, the protection qualities of the helmet have been compromised.
Goggles are another item you'll want to take good care of. They do a good job of protection your eyes and shielding them from flying rocks and debris. Over time your goggles will get small scratches in them from doing their jobs and this will make your visibility less than 100%. A quick fix for the scratches is to use a soft clean cloth, like an auto detailing cloth that has no fuzz or lint - a microfiber towel would be best, and spread some Pledge furniture treatment on the lens, use a small bit at a time and rub off the excess. The little scratches on your goggles will be filled.
The best reason to keep your helmet and goggles maintained, is so you don't have to keep buying new ones. Keeping your helmet and goggles clean and ready to use will give you many more hours of safe riding.