For a more reliable result, place the eggs gently in a saucepan and cover them with cool water. Bring the water to a boil over medium heat. Once it starts boiling, reduce the heat to a gentle simmer and cook according to how firm you want the yolks. When they are done, transfer the eggs to ice water. This stops the cooking process and also makes them easier to peel. If an egg does crack during boiling, a little white escaping into the water does not necessarily mean the entire batch is ruined. But if you want smooth, intact shells, the biggest safeguards are simple: avoid sudden temperature changes, handle the eggs gently and keep the water at a controlled simmer rather than a furious boil.