I really must disagree with using pepper to learn the game. Yes, it gives you the volume of touches you want, but it isn't game transferable.
How often is a ball attacked below the plane of the net in a normal game? How often do you dig the ball back to the person who just spiked the ball, don't you want the ball redirected to a setter? How often do you get to attack without moving your feet? How often do you get to play defense without re-adjusting your position?
I got dinged for that when I did my provincial coaching evaluations (the person who did my eval btw was the asst coach to the national team). After that experience, I rarely use artificial drills.
Yeah, there are a lot of good stuff on youtube, but you'd have to be fairly careful with the instruction, sometimes, they're missing KEY points to the technique. See if they mention anything about the alignment: feet, hips, shoulders, platform, etc. AND getting into the right alignment. If they're just talking about just the touch on the ball then it's absolute rubbish, you won't touch the ball right if you're not in position to do so in the first place.
Best way to learn to play the game, I find, is to play small sided games. 2 vs 2 in a 3 metre by 3 metre court (attack line to attack line with one third of the net width). If you're feeling confident, 2 vs 2 in a 3 metre by 9 metre court (end line to end line with one third of the net width). Once the ball crosses the net, you and your partner switch roles, say if you were just playing defense last you now play setter, and vice versa.
This, I find, is better than playing pepper because you're actually forced to move and adjust to what's going on. Also your ball handling is forced to improve because you're playing in a smaller court. Again, it's game transferable because the amounts of time that you're made to focus on the task is similar to that of a normal game.
If you're just starting, I'd do the same format as above, but allow you to catch the ball and toss it to your partner, later move to actual volleyball touches but to account for touch errors allow one bounce each time the ball is on your side of the net, eventually remove the one bounce rule, and you're playing the full game.
(1) DON'T STARE AT THE BALL the whole time, glance at it to know where it is. The ball won't tell you anything about where it's going; watch the people touching the ball to get an idea where the ball is actually going to go after it leaves them.
(2) MOVEMENT is key! Always move to get into the best alignment possible; otherwise, that's where errors come in 'cause you're reaching too much or you're out of position, etc.
(3) FEET FIRST hands/arms next. I've seen people trying to run while keeping their hands together as if to pass or hands over their head as if to set. It's not at all effective. You won't get very far if you're forced to move quickly that way.
Best to keep your hands about waist high, right til the moment you make that pass/set.