Depends whether you go for temporary ones, gel tips and overlays or acrylic. I personally love gel nails but you do need to give your nails a week or two off from them every so often to stop them becoming weak under the tip. Nails do grow under the gels and tip but I don't think it grows in as strong - but that might just be me.
I personally would try growing them out as much as possible naturally, but file them if they break so they're not left cracked etc. If you grow them out that way, you'll reduce the amount of splits etc, especially if you use a fortifier (Sally Hansen do them) once a week or so. It'll be hard to have false nails sit on nails with splits, ridges, cracks etc regardless of what you choose so its best to try and strengthen your natural nail first.