What should you do if someone is following you closely before slowing down?

Flashing your brake light is an effective way to alert a driver who is following you closely that you are about to slow down. This action gives the following driver visual confirmation of your intention to reduce speed, which can help prevent a potential rear-end collision. The brake light acts as a signal to inform others on the road of your upcoming change in speed, allowing them to react accordingly.

Using your hand to signal can be ambiguous and is not as easily noticed as brake lights, especially during low visibility conditions. Checking your mirrors is certainly important for overall situational awareness, but it does not communicate your intentions to the driver behind you. Accelerating suddenly is dangerous and can increase the likelihood of an accident, especially with someone following too closely. Hence, flashing the brake light stands out as the most appropriate and effective response in this scenario.