A pocket knife/multitool can be handy in a wide variety of situations. It’s useful for tasks as large as building an emergency shelter or lighting a campfire with poor fuel, or as small as repairing a damaged backpack. Keep you knife sharp and clean, and don’t forget to first earn your Totin’ Chip.
A first aid kit can be a lifesaver. Literally. A few items will allow you to treat scratches, blisters and other minor injuries. They should also allow you to provide initial care while waiting for help for more serious injuries.
Bring extra clothing to match the weather. Multiple layers are better than a single massive jacket, because layered clothing is adaptable to a wide range of temperatures.. Try to avoid cotton.
Rain gear is very important. Rain can come in a hurry, and getting your clothes drenched is more than just uncomfortable, it can lead to hypothermia, a potentially fatal condition.
A flashlight/Headlamp or a rugged penlight is important for finding your way in the dark. Bring extra batteries, too! LED headlamps are preferred to have a red light option for preserving night vision.
Trail food is good for maintaining your energy. Bring more than you think you’ll need in case you get stuck (or lost) in the woods.
Water/WaterStorage is probably the most important of the Essentials. It can prevent dehydration, heat exhaustion and heatstroke. Use a lightweight, unbreakable container with a secure lid. The human body may only survive for a few days without water. Portable water purifiers and water stills may be used to obtain potable water from virtually any source.
Matches/Fire Starter may be used to light fires for heat, or for signalling purposes. Store matches or lighters in resealable plastic bags or a water tight container.
Sun protection may include sunblock, sunglasses, lip balm, and a wide brimmed hat. Used properly, it will prevent sunburn and possibly heat exhaustion.
Map and compass are probably the most important tools you can carry in case you get lost. In knowledgeable hands, they can be used to determine one's location and the best route to reach another location.