Your comfort level in properly controlling the throttle and the front brake will play a major role in your ability to cover the lever. If you're unsure of your throttle and braking technique, take a MSF class. When covering the front brake, try various numbers of fingers until you find out what works best for you. Some people prefer to use all four fingers, while I generally use two with the remainder giving me a firm grip on the throttle. Before you actually ride on the street, sit in your driveway and practice rolling the throttle on and off while covering the brake. If you have trouble closing the throttle completely, release it and place your hand on the grip with your fingers resting on the brake lever. Then, wrap your fingers around the grip and try opening and closing the throttle. Next, roll off and apply the front brake. The motion should be as smooth as possible. If the lever traps your fingers against the grip when you apply the brake, try adjusting the lever or bleeding the brake line. If the problem remains, you will need to cover the lever with four fingers. Once you feel comfortable closing the throttle and braking simultaneously, try it in a parking lot and then move to the street.