I try to raise the hand corresponding to the direction that I'm going to point. For example, if I'm trail, and team A is on my right, and they call timeout, I'll raise my right hand and point right. If, however, team B wants the TO, I'll raise my
left hand, and point left. Team A travels - left hand up, signal travel, use left hand to point left. Keeps you from looking like your directing airplanes if you try to only use one hand.
I usually always raise my right hand for fouls, though.