Drive slowly and keep to the speed limit. Driving at 20mph on a dry road, your car has a stopping distance of 3 car lengths. On a wet or muddy road that distance doubles.
Don't drive too close to farm vehicles. Give them room for their manouvres and remember that if you wish to overtake them then driving to close will impair your view. The more distance between you and them, the more vision of the road ahead you will get.
Beware of livestock. Unfortunately cows and sheep cannot read and are prone to walking out into the road. Also farmers sometimes need to move a whole herd from one field to another. If you are caught like this turn off your engine and wait patiently for the cattle to pass and only then drive on.
Keep an eye out for warning sign as these will give you advance warning of any hazards ahead.
In the evening at the first failure of light turn on your headlights. This will give other drivers warning of your presence and vice versa. Make use of safety devices such as chevrons, cats eyes and warning signs.