A useful tactic to learn and use is the “contact and cover” approach. Typically used in law enforcement, it can also be a useful civilian self-defense tactic when you are working with like minded individuals.
“Contact and cover” is the approach used when dealing with a subject who is an unknown threat, or if you are approaching/approached by an unknown threat(s). In other words, you are not in a position to use or threaten to use force, but you are in a situation where caution is advised.
When you divide the subjects attention you take advantage of the OODA process to tilt the situation in your favor. Thus, the “contact” person is the individual who talks to or otherwise deals with the subject while the “cover” person takes up a position where he can observe and react to what what transpires. Typically, the “cover” will try to find a position on a flank of the “contact”. Sometimes a position behind the subject can be advantageous, but comes with the risk of being hit by friendly fire. It’s important to remember that the contact person is the one who does all the talking/dealing with the subject, the cover’s job is to remain undistracted and aware; aware of whats going on in the immediate area and aware of who may be approaching the area.
When I am a cover officer I attempt to position myself near an available source of cover should things take a turn for the “lead flying worse”. If possible I also like to place myself near or blocking an avenue of escape in case the subject decides to “beat feet”. I also advise that officers work out a code word that the contact officer will say when he intends to go “hands on”. This lets the cover officer know what is about to happen.