As always, number one is to practice conflict avoidance and situational awareness. Leave yourself always an out and keep your eyes open about what is going on around you.
Next is to clear your over garment when you get in the car. This does a couple things. It gives you clear access to your weapon and it also covers it to avoid problems with passer and drivers by.
Keep muzzle awareness in the vehicle. It is very confined inside a car or truck and if the weapon goes off as you engage you want it going off in a safe direction.
Remember to know your target, what is in line with it and what is behind it. You own that bullet when you let it go.
As mentioned in the video, training is important. Think about getting or renting an airsoft gun to get the practice you need.