Three Columns or Puff of Smoke Are Distress Message
Number one rule of rescue if you are stranded is to stay near your vehicle or aircraft, because it is more likely to be seen by search aircraft.
Keep a small fire going all the time and have materials near by such as a pile of damp leaves or pine needles which can be added to the fire to make a thick smoke. Use a blanket or poncho to briefly cover the fire, then expose it to release a large smoke "puff". Three such smoke puffs are a recognized distress signal.
More likely to be seen is to set out three containers, which are accessible, but well separated by about 100 feet. Use vehicle hubcaps, empty ammunition or food cans into which is placed oil-saturated seating foam, rags, etc. which can be quickly ignited by a firebrand from your warming fire to produce a thick smoke. In daylight sweep the horizon with your signal mirror every hour at the top of the hour, whether you see or hear any aircraft or not.
For more info see:
http://www.inquiry.net/outdoor/native/sign/smoke-signal.htm
http://www.wilderness-survival.net/chp19.php
http://www.boatus.org/onlinecourse/ReviewPages/BoatUSF/Project/info2f.htm