Take some time and read the attached PDFs. These are just useful information.

Courtesy of Wikipedia, the Ten Essentials that should always be included in your packing List

A pocket knife

(presumably more than just a knife, a Swiss Army knife for example) can come in handy in a wide variety of situations. It is 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.

A first aid kit

can be a lifesaver. A basic kit for first aid might include adhesive bandages, medical tape, sterile gauze, moleskin, soap, antiseptic, a mouth-barrier device for CPR, and scissors.

Extra clothing

to match the weather. Multiple layers are superior to a single massive jacket, because layered clothing is adaptable to a wide range of temperatures.

Rain gear

is very important. Being wet from rain may result in hypothermia, a potentially fatal condition.

A flashlight

is, of course, important for finding one's way at night.

Trail food

is good for maintaining your energy. However, the human body can reportedly survive for weeks without food, so starving to death should be the least of your worries if you become lost in the wilderness.

Water

is probably the most important of the Essentials. Dehydration may develop into heat exhaustion and heatstroke. 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. If a watersource is unavailable the use of a dromedary bag should be considered.

Matches and or a firestarter

may be used to light fires for heat, or for signalling purposes. (Publicly owned forests in the United States often have lookout stations for forest fires and signal fires.)

Sun protection

may include sunblock, sunglasses, lip balm and a wide-brimmed hat. Used properly, it will prevent sunburn and possibly heat exhaustion.

Trail maps and compass

are probably the most important tools one can carry in case of getting lost, but they won't be of any use to someone who does not know how to use them. In knowledgeable hands, they can be used to determine one's location and the best route to reach another location.