Having effective counter striking from the shield is crucial to keep a fighter from getting overwhelmed by strikes. You need to concetrate on the "focus of force" with your basic strikes (jab, cross, hook, uppercut) and elbow strikes from your shield, Counter strikes require a two step action for effective force delivery from the shield. Counter striking can be hard to do at first, but with some practice you should be able to develop quick and power blows with good accuracy. The key points to be made here are to focus on finding the "proper line of force", which is the specific funcional vector for an energy to take. This line of force needs to activate your body's strongest driving muscles for max power. Your strike needs to start on the proper line of force from the point of concpetion to its target. If it does not follow the line of force you will not have the power and strength you need to cause damage  It's important to make sure your strikes have explosive power behind them  in which should drive the target back (4-6 inches of penetration), or through it.Try to minimize your telegraphicing and maximize your speed, recovery time, and stay strong through the entire range of motion, allowing you to get back into your shield quickly.