Final answer:
When oncoming vehicle's headlights are too bright, adjust your rearview mirror and avoid looking directly at the headlights.
Step-by-step explanation:
When an oncoming vehicle's headlights are too bright, you should take certain measures to ensure your safety. One of the best ways to deal with bright headlights is to adjust your own car's rearview mirror. This can be done by flipping the mirror to its nighttime setting, which will reduce the glare from the oncoming headlights. Furthermore, you can also look slightly to the right side of the road rather than looking directly at the headlights. This way, the bright light won't affect your vision as much.