Controlling an aerial ball to one of your team-mates can be very useful. The two basic elements of a good cushion header are to head at a good speed and height for your team-mate. They wants to receive the ball so that they can do whatever they needs to do with it instantly.
Step 1: Drill 1
Throw the ball up to yourself and head to your partner's hands, take it in turns until you have completed five each. Then throw the ball to your partner to head five back to your hands. Then get your partner to throw five to you to head back to him.
Step 2: Drill 2
Get your partner to throw the ball to you. This time head it down to him to control with his feet or knees back into his hands do five and then throw for your partner to head.
Step 3: Drill 3
Throw the ball up for yourself and head to your partner to head back to you so you can catch. Do five of these and then just keep the headers going as long as you can. Keep a score and see how many you can do.