During the Trip

Carry the 10 Essentials. Consider also carrying a spare flashlight, a pencil or pen, and a stash of emergency food (such as energy bars) that you promise yourself you won't consume during hunger attacks earlier in the trip. Tote a lightweight space blanket, too; it could help you more comfortably endure a chilly night.
Check your map regularly, even if you are walking on an obvious trail. Get acquainted with seeing how markings on a map depict the topography all around you.
Learn basic map-and-compass navigational skills. Some good starting points:
Review this navigation clinic (courtesy of REI).
Stay together! If members of your group begin hiking separately, someone might get mixed up at a trail junction and get lost.
Carry a whistle and keep it within easy reach. If you become lost or injure yourself, don't rely on easily fatigued vocal chords to signal for help. A whistle lasts longer and its sound carries farther. Make sure your kids are individually equipped with whistles. Some people carry whistles attached to the shoulder straps of their packs for easy access.
Tip: Three blasts of a whistle is a universal signal for help.

Wear a watch and know what time sunset occurs. Autumn hikers, still accustomed to long summer days, often overestimate the amount of daylight available to them.
Avoid overconfidence. Some people believe getting lost only "happens to other people." Put away your ego and regularly double-check your position and your understanding of where you think you should be. If the two don't match up, stop and reevaluate. When you reach major terrain features - a trail crossing, bridge or shelter - see if you can locate that feature on your map. This will assure that you know where you are.

This clinics was borrowed from the REI website
Advisers to this clinic:
Rick Hood, director of Navigation Northwest (www.hoodcs.com), a search-and-rescue education service. Bob and Mike Burns, authors of Wilderness Navigation: Finding Your Way Using Map, Compass, Altimeter and GPS (The Mountaineers).