One way to help prevent and treat nail problems is to practice good nail care and hygiene. Wash and dry your hands properly, which means lathering up with warm water and soap and scrubbing for at least 20 seconds -- about the time it takes to sing "Happy Birthday to You" to yourself twice -- and scrub everything from the back of your hands to the spaces between your fingers. And don't forget to clean underneath your nails, where not only dirt but bacteria and fungus can hang out. Dry your hands (and feet) thoroughly to discourage fungal growth.
In addition to practicing good nail hygiene, you should keep nails and cuticles hydrated by applying moisturizer daily. Try petroleum jelly or olive oil, or choose a thick, creamy lotion that contains lactic acid or urea to help prevent cracking. And stop biting your fingernails -- not only will your chewing damage the skin around your nails, it also leaves nails susceptible to infection from bacteria in your mouth.