Well, I don't know yet if recent changes in my vitamin routine is improving my overall health or not. Nor, can I tell if it's doing anything for my hair, which is one of my goals. It's a little too soon to tell. However, I do think it's making my nails grow faster and, perhaps, stronger too. I'm not sure if it's my imagination, but I also think the nail bed color is healthier looking, too -- not that I had a problem before.
I am hard on my nails, though. I really must remember to wear gloves in the kitchen, when cleaning bathrooms, and when gardening! The people I know who have the prettiest nails do protect their hands when doing these kinds of chores.
Here's an article that probably tells you more than you ever want to know about your fingernails.
Here's a slide show about how to have pretty nails.
Here's an article from the Mayo clinic about how to have healthy nails.
The article from Mayo states, among other things, not to let a manicure technician clip away the cuticle, as this can open the area around the fingernail to infection.
I adore getting the occasional manicure and pedicure. However, I do think that I've come away with two little annoying foot problems from a pedicure. I learned the hard way not to let a technician buff your feet with too much pressure and also not to assume that the tools they are using are sanitary.
Some nail salons dedicate a set of tools to each regular customer. If you don't go often enough for that or your salon doesn't provide that service, you can bring a set of your own tools just to make sure they are clean.