The following are the keys to good blocking. Assess your own blocking to determine which keys you can improve, then work on one at a time until you are a great blocker. Know the hitters. Blockers absolutely must know which players are the hitters. Know your job.
Blockers know their primary blocking responsibilities.
A middle blocker's primary job may be to block the quick attack, then try to block any other attack. An outside hitter's primary responsibility may be to block the live setter, then block any other attack. Stand at the net. Blockers never move towards to net to block. This may give you an extra inch of vertical, but will cause more net violations and sprained ankles.