Throw the ball in the air and bend your legs, with arms out in front. Bump the ball up using mainly leg movement not arm swing.
Keep it going, changing which arm you bump the ball with (try and use good rhythm and mainly legs).
New hitters rarely miss because of their arm. They miss because of their feet. Build a reliable approach, then time it with your setter.
When your hitter gets stuffed, five teammates standing and watching is how you lose the point. Good attack coverage turns a blocked ball into a second swing.
Coaches spend hours correcting arms in serve receive when the real fault is almost always the feet. Fix the movement and the platform fixes itself.