One proven and effective trick is to always have extra BDUs and boots in your home and car. You may have to put them on in a hurry. Because you might not have time to change, particularly during active-shooter situations, you'll deploy rapidly and "as is," which may mean you're still wearing gym clothes.
Mistaken identity police-on-police shootings are the result of not recognizing or realizing the armed individual is actually a LEO. Badges alone aren't enough, because they're only visible from the front.
This is why so many LE agencies require plainclothes officers wear raid jackets with highly visible "POLICE" on them. Other agencies, especially in the northeast U.S., employ the "color of the day" to recognize plainclothes LEOs.
However, there is one product available to LE today that greatly reduces the potential of misidentification "friendly fire" involving non-uniformed LEO's involved in critical incidents. This ground-breaking product is the DSM (Don't Shoot Me) Safety Banner, which is highly visible from 360 degrees, easily deployed and inexpensive.
Manufactured by DSM Safety Products, the DSM Safety Banner is the creation of Sgt. Mike Lessman, a veteran Reno (Nev.) PD SWAT officer. The DSM is low cost, lightweight, easy to carry, and deploys rapidly. Best of all, it provides immediate "POLICE" recognition both front and back.