netspazz,,
We signal our outfielders, different ways. When we want them to play back, we signal with our hand over the top of the hat, like a salute except missing the hat. We then tell them nothing over your head. When we want them to play in, the signal is the back of the open hand working like a shovel in a downward motion. Standard side to side alignment is, bases extended in right and left. When we want side to side adjustments, we do just like the traffic cop, one hand up for any depth adjustments, and the other hand will dictate direction we want positioning to.
However, as Coachric stated, the more you know about your opponent and your pitching staff will help your alignment as much as any signs.