Fingernails can become brittle and chipped if the body is not receiving certain proper nutrients. Biotin is a vitamin that helps the body process fatty acids and proteins. Take a biotin supplement of 2.5 milligrams per day to strengthen your nails. Another important vitamin for fingernails is the B vitamin folate and it can be supplemented in a daily B vitamin complex. Make sure you are getting adequate protein in your diet, with at least several servings of meat, dairy or nuts per day.
You can moisturize your nails just like you would your skin by rubbing moisturizing lotion into them. This is especially important after you remove nail polish and after the nails have been in water. Applying a treatment "nail polish" to your nails actually keeps in moisture, which is why it can be effective in preserving damaged nails. OPI has a great "polish" called "Nail Treatment - Hydrator" which you can find at: http://sephora.com/browse/product.jhtml?id=P219339
I hope this helps you.