Hand and arm signals are a great way of communicating when you don’t want to be heard. quieter and often more reliable than whispering into a radio mike. You should have a standardized set for your cell. When on the move, shoot an eye towards your cell members every ten or fifteen seconds in case they are trying to signal you. Get in the habit of passing the signals on: when one member of the cell uses a hand and arm signal, everyone who sees it should repeat it. That will let the signaler know that his sign is acknowledged and increases the chance that the intended recipient (who may be looking away at any given moment) will get the message.
A few common signals used by military and SWAT teams are shown below. You can use them as is, modify them for your purposes, or make up your own from scratch. But in any event, have a set that everyone in the cell knows and recognizes. Then use them.
Standardized Hand Signals For Close Range Engagement (C.R.E.)
Source: Airsoft Gent