Never undertake a walk in wilderness country alone. Three is a recommended minimum group size.
Wear or carry suitable clothing, food, basic first aid kit, survival bag, waterproof torch (one on an elasticated headband is best) & whistle.
Know how to read a map and use a compass. Always carry both and use the map to maintain a check on your location and rate of progress.
Know the weather forecast; be alert to changing conditions en route.
Leave a note of your planned route and expected arrival time. Report on arrival.
Carry a mobile phone; only use it to summon Mountain Rescue in a real emergency -incapacitating or serious injury or illness.
If an emergency arises stay calm and think before you act. If summoning help first identify your location (grid reference), then contact Emergency Services (999 or 112) and ask for Mountain Rescue.