When drilling the shield with a partner, start the drill in the shield first as opposed to being in your guard stance. It will be easier to grasp this way. First, start the drill one person as a designated hitter and the other the shielder. The shielder should get comfortbale having his/her limbs as close as possible to their head. (remember to keep your head and chin tucked in the pocket). Second, get your body into a stable position to resist and asborb force, (drive, brace leg is a must). Third, have your partner throw one random attack at a time and focus on closing off the area or zone in which you preceive the attack, making sure you don't close your eyes, or pull your head away from your arms. Don't lean away, or retreat from the attack. Instead force yourself to stand your ground and stop any random strike(s) without reaching out to block. When you get comfortbale doing this volley back and forth with your partner shielding eachothers strikes. Work the upper gate (head region) first. Rermeber this is just a drill, don't make it a sparring match, trying to score on one another just yet. Focus on doing a proper vertical shield first.