I keep my nails short these days as I type so much, but when I used to grow them out I found that eating foods rich in gelatin immensely helped the growth. Jello, tapioca puddings and certain brands of yogurt contain high percentages of gelatin. Also, if you lotion your hands often this helps to protect the nails. Filing them often, at least the ends, along with a careful buffing minimizes tiny snags (and even the tiniest of snags can lead to chipping). And just like your bones, hair and teeth, nails need protein to be healthy. So don't scrimp on protein in your diet.