We lose about 100 hairs a day, normally. There doesn't seem to be much we can do (yet) to avoid genetically determined hair loss. The best you can do is to treat your scalp and hair lovingly. Gentle shampoos, do not brush vigorously (none of that old 100 strokes a day stuff), comb out gently, no hot dryers, or lots of tight updos. Good nutrition, and at the very least, a good multivitamin daily.