You can do this as a nice warm up to get the players minds working. 

These simple ideas are designed to get (forces) players to look away from the ball but at the same time be able to control and pass the ball accurately when it comes. It can be 1 touch or 2 touches. This prevents them from just being focused on the ball as it is arriving and therefore not being aware of their immediate options.

Its all mental training and if you do it quickly then the players have to be constantly looking and thinking BEFORE receiving the ball and making successful decisions and accurate passes. Players are required to look AWAY from the ball to see the signal and then make a decision. They can often see the ball in their Peripheral vision anyway as they look away from it.

Increase the challenges as you see fit, reducing the number of touches, by reducing the amount of space between players. Even ask the signaling player to make the signal as late as possible but still giving the players split second time and a chance to see, decide and perform the correct action before receiving the ball.

Try to get a good rhythm going with the signaling and decision making and passing and moving; so we have constant play with no interruptions and the thinking process is constantly tested.

Awareness Challenges with Players in 2s

(C) Offers 4 challenges: right hand up, left hand up, no hands up, and both hands up.

Players must look away from the ball to see what decision (C) has made and then call out what (C) has done. At the same time one touch passing accuracy should be maintained. You can introduce 2 touch passing with certain footwork challenges also. Start at a distance and reduce it, say 10 years apart to start. This is a very easy introduction to the look; think and decide.

Once they get good at this decrease the distance between the two players so less time to think and anticipate and decision make. Now maybe 5 yards apart. Rotate the players so everyone is involved in the thinking processes developed. Make it competitive and each player counts how many times they made the wrong decision and hence the wrong pass; perhaps because they forgot to look away from the ball in the first place and just focused on the ball as happens VERY often in the game itself.

Awareness Challenges with Players in 3s

(C) Offers 4 challenges: right hand up, left hand up, no hands up, and both hands up. (A) Point right, moves left. (C) turn left; in the hand direction and passes right). (A) moves to the left cone to receive the pass.

Now (C) must receive the ball and work between the two players (A) and (B). Before (C) receives the pass off (B), (C) must look “behind” to see what (A) is signaling. Same ideas; right hand up, left hand up, both hands up (pass back), no hands up (Receive and Turn). If the right hand is up then (C) receives and turns to the right and passes to the left, so the turn is in the direction of the hand; but diagonally opposite with the pass. Here (A) holds the right hand up and moves left.

(A) Brings the ball back with one touch to the middle cone and we start again.

Now (B) must decide where (C) plays the ball by performing the hand signals. Both hands up and (C) must pass the ball back to (A), no hands up (C) must receive and turn and pass to the middle cone to (B). Here (B) has both hands up so must pass back to (A) at the middle cone. 

Make it two touches but the middle player now must move side to side and turn their body to receive the ball going the opposite way.

Here (C) comes off at an angle to (A) and (B) getting side-on to have better peripheral vision. As (C ) is moving he or she must be looking at (B) to see what signal they have made to then decide what pass they make. (B) obviously put up the left hand so moves to the right. (C) receives and turns to the outside or left and passes to (B)s left.

As in the 2s idea have it competitive and players count how many decisions they got wrong to test against themselves and also against each other.

(B)'s first touch is back to the middle cone and 2nd touch is a pass to (C) who has switched positions in the mean time. As all this is happening (A) has signaled with NO hands up so (C) must receive and turn and pass to (A) at the middle cone as shown. Now (C) can turn inside or outside. Next, (A) waits until (C) is in position on the other side to then pass the ball.