My nails keep crackig, splitting, and breaking, what's wrong and what can I do about it?

Our fingernails 'mature' at about 15 years of age, after that, it's all downhill. The nail bed transmits a constant tidal flow of oils and moisture up through the nail plate layers. The oil and moisture acts as the 'cement' to hold the nail plate layered together. As we age, this 'tidal flow' diminishes to a drop or two; not nearly enough to prevent splitting, cracking and peeling. This is a very easy problem to solve! Go to a Sally Beauty Supply (nationwide) and purchase a bottle of Botanical Oil. This oil contains Jojoba, Vitamin E, Rice Bran Oil, Camomile Oil and Passion Fruit Oil. Jojoba oil has the tiniest molecule that can penetrate the nail plate layers and draw the other larger moleculed oils in after it. Vitamin E is an anti-aging oil that will work to prevent the production of free-radicals that contribute to the aging process. The other oils will condition and moisturize the nail plate layers. This will help to heal the splitting, cracking and breaking and also will help to lessen vertical ridges; it will help return your nails to a more flexible' condition. In other words, it will give you back some of your youthful 'nail health.
http://www.healthboards.com/skin-hair-and-nail-problems/543.html

I need long fingernails on my right hand for playing classical guitar. I tried different things, and settled on using a vitamin supplement and an oil supplement to avoid cracking, splitting & breaking.

1) take 5 mg of Biotin in the morning
2) rub a little ONYMYRRHE into the nails at night

Cauliflower contains a nutrient called biotin. This can thicken the nail to prevent splitting or cracking.

Also, a regular soak with vegetable oil is effective.

Seriously... check out this site.
http://www.mothernature.com/Library/Bookshelf/Books/48/25.cfm