Posters are one of the most important tools in the recovery of almost any lost pet.  Several pet detectives with search dogs have found that 80%-90% of recoveries were ultimately due to the posters while only 5%-15% were directly due to the search dogs.  Flyers can also be useful, especially when hand delivered door-to-door.  To be effective, flyers need to be read while in-hand or posted for a person on foot to read. 

The biggest mistake that people make is treating flyers like posters.  

You MUST create large, brightly colored posters that people can easily read from a distance.  The most effective posters can be read while someone is sitting inside their car.