This is for a former student of mine who is now doing some teaching... and is trying orchestrate a recreational-level volleyball game. HAVE FUN!
First - the HANDS - the most important part is to have the fat part of the thumbs together and the thumbs aligned and parallel. This means that your "platform" for passing is even. If, say, your left thumb is higher or over the right thumb, this will inevitably make your left wrist higher than your right, and your left forearm higher than you right. Subsequently all of the balls you passed will shank off to your right. Having bad hand positioning can make all your anticipation and ability to move fast be for naught.
You can see that my preference is to ball my left hand into a fist and cup my right around it.
Second - the ARMS - hold them straight out in front of you. Hunch your shoulders a little. Believe it or not, you're not really going to swing your arms at all. Whatever you do, don't swing your arms higher than your shoulders.
Third - the FEET - place them just a little wider than your shoulders with your right foot a bit further forward. (If you're left-handed, it'll come naturally to put your left forward.)
Fourth - the LEGS - bend them. Get low to receive the ball and extend your back leg and come up through the ball. The ball should go the direction your hips and shoulders are facing.
Of course... you have to do this each and every time you pass the ball... AND that ball is not going to come right to where you're standing every time. So, you're going to have to move to get yourself into this position so that you can pass it. If you have to run, run with your hands apart and then put them together at the last second. If you have to go to one side, shuffle over there to keep your hips and shoulders facing where you want the ball to go.
Passing is the absolute key to the game. Nothing happens without it. Though sadly, it's the passers on the team who never get enough credit for their skills. They're the ones who start the offense. They're the ones who prevent the other team from getting a kill. It all depends on them.