Disturb the natural appearance of the area such as with brush, rocks or dirt. Lay out signals and start a controlled fire. Three fires set in a triangle is an internationally-recognized distress signal. Generally, a fire can be built using any available fuel such as wood, a car tire or a car seat, which has been taken out of the vehicle. In daylight hours, it is better to have a fire produce black smoke like a tire fire.
Bright fires are best at night.
Keep the fire burning at all times, if possible. If your fuel is limited, keep a small kindling fire burning and have your resources nearby to make the fire bigger in case you see someone who could come to help. There are other distress signals which you can use. In a clearing, use newspaper or aluminum foil weighed down with rocks to make a large triangle. This is an accepted distress signal.