We have all been taught to flood a stopped vehicel with takedown lights, high beams and spotlighting the driver's mirror. Instead of approaching driver side, exit your vehicle, take a quick glance to the rear for traffic and walk backwards slowly with the back of your right hand brushing you patrol car. Take a quick glance to the rear one last time and by this time you should be behind your patrol's trunk. This should take less than 2 seconds.
You are now in perfect cover in case the driver or passnegers exit with a weapon. From this point approach with caution. I always approach on the passenger side. There are numerous advantages to the passenger side approach. You chances are less of being hit by vehicle, ambushed from a passing vehicle and the very least you surprise the driver. I have this to be literally a life saver several times.