You catch sight of a life-list bird and stop to take photos, telling the group you'll catch up soon. Ten minutes later, you stow your camera and set off briskly, only to realize after a mile that the trail you're following isn't a trail at all.
Stop. "Lost hikers can make their situation much worse by moving in haste," says John Race, owner and guide at Washington's Northwest Mountain School. Instead of shouting, blow three short blasts on a whistle. In most cases, your friends will be looking (and listening) for you. If not, mark your present location with sticks and attempt to backtrack to the original trail. If you can't find it, or get more disoriented, return to your original lost location, find a visible spot to wait, and signal for help. Bushwhack to regain the trail only if you can see your destination, have good navigation skills and a compass or GPS, and won't encounter impassable terrain.
Once you regain the trail, attempt to follow your group. If you don't know which direction to take at trail junctions, stop and signal with your whistle. Your friends will find you there.