Before you leave home, always tell a friend or family member where you plan on going and when you plan to return. Leave them with instructions on what to do, including the proper authorities to contact, if you don't return on time.
In case of an unexpected problem or emergency, always have a back-up plan for escaping the area safely. Also provide this back-up plan to your friends or family before you leave.
Although it's sometimes nice to be alone in the outdoors, it's always safest to go with at least one or two partners, especially if you're a novice or unfamiliar with the area.
Have the appropriate level of knowledge and experience for the adventure you plan to have. If you are a novice, please rely on a professional guide or at least a highly knowledgable and experienced partner.
As much as possible, study and become familiar with the area you plan on exploring. Gain a thorough understanding of the terrain and its potential hazards.
Review the local weather forecast in the area you plan on going and take the appropriate clothing and equipment. During winter-like conditions in mountainous terrain, check the current avalanche report in the area.
Be healthy, safe, and smart. Know your limits, don't over-extend them, and don't take unnecessary risks. It's advisable not to go hiking with an existing injury, as it could become unpredictably worse during activity.
While in the backcountry with young children, always keep them within sight. If your dog is with you, be courteous and keep it leashed in areas that require it. Doing so will keep you, your dog, other people, and the wildlife more safe.
Be aware of your surroundings at all times. There are many objective hazards in the wilderness, and they aren't always obvious. Keep a keen eye out for deteriorating weather, dangerous trail conditions, avalanche risks, and wildlife.
Be prepared! Always plan for the worst and hope for the best. Carrying a few extra items can save your life. At a minimum, always carry the "10 Essentials":
Extra food and water (more than you think you'll need)
Extra clothing (more than you think you'll need)
Map and compass (know how to use them)
Flashlight or headlamp (plus extra batteries)
First-aid kit
Fire-starting kit
Pocket-knife or multi-tool
Signaling device (mirror or whistle)
Sunscreen and sunglasses
Emergency shelter (emergency blanket or bivy sack)