The first rule, or even the most natural response while driving in fog is to reduce your speed. Fog limits a driver's visibility, so it is important to drive slower than usual to give yourself more time to react to hazards on the road. Increase the distance between your car and the vehicle ahead of you to allow for extra reaction time in case of an emergency. 

When driving in fog, avoid using high beams. Your high beams reflect off the moisture in the fog, causing glare that further reduces visibility. Instead, use your low beams and fog lights if your vehicle is equipped with them, as they are designed to cut through fog and make it easier for you to see further down the road.

In thick fog, it can be hard to see other vehicles, pedestrians or obstacles. In such a situation you can rely on road markings like the white or yellow line on the side of the road to guide you. This can be more effective than trying to see other cars or traffic signs that may not be clearly visible in dense fog.

Sudden braking or sharp turns can lead to accidents in foggy conditions. Driving smoothly and signal your next move on the road with your indicators can help other drivers by allowing them to understand the situation and giving them ample time to react.

Fog can cause moisture to accumulate on your windshield, further reducing your visibility. Turn on your vehicle’s defogger and turn your vents blow air onto the front and rear windshields. For mist accumulating on the exterior of your vehicle you may use your windshield wipers. Keeping your windows clear is essential for safe driving.

Fog makes it difficult to judge distances and overtaking can be especially dangerous. If you need to overtake, do so with extreme caution and only when you have clear visibility of the road ahead. It’s often safer to stay behind the vehicle in front of you while maintaining a safe distance until the fog clears.