Come on the brake smooth and firm as needed and disengage similarly smooth. Emergency braking and riding the brake can both heat up the brake system significantly. Pay close attention when the brakes are hot and do what you can to avoid applying the brakes while stopped. When the rotors and pads are really hot and the brakes are applied while stopped, excess pad material is deposited on the rotor in a single spot. This creates a high point on the rotors and is often the culprit for your vibrating or shuddering under braking which is commonly though incorrectly referred to as "warped rotors". The worse it is the more you will notice it and at slower speeds.