Healthy nails are the foundation of any manicure, gel or otherwise. A few habits go a long way: moisturize your cuticles daily, take a short break between gel applications so nails can breathe, and always let a professional remove gel rather than peeling it off at home — peeling takes several layers of nail with it.
If your nails are peeling or brittle, a course of nail-strengthening treatments alongside a biotin-rich diet usually shows results within a few weeks.