If you're talking about nail tips - I've found them to be nothing but trouble. I've kept my nails fairly long since maybe 7th grade. A week before my senior prom, I broke one nail badly, so I put a tip on just that one nail. It looked great, but that nail became incredibly weak, and it took a long time to grow out.
I still keep my nails pretty long (oddly enough, it doesn't interfere with my typing) but I don't wear nail polish... I just keep them shaped and buff them from time to time.