[WI REF]

May regular partner and I use several signals throughout our games.
One of them is the pointing to the wrist during an inbound situation to inform each other of a last second shot. That is a quick reminder as to who will have the last shot call.

We also use a closed fist during a dead ball situation to let each other know to tighten up the calls some. That way we are on the same page with each other as far as the calls go.
Sometimes we might use and open hand to let each other know to loosen the calling up some and let them play. Usually the coaches and fans are already telling us that anyway.

Your biggest asset is to just make sure that you have good eye contact with your partner at all times. You don't want to surprise him/her by putting the ball into play when they aren't in position. Make sure that you aren't afraid to discuss a situation during a TO near the end of the game in order to be ready for anything.
A good pre-game and communicating again at half time will always help too.