Make flyers, using good, clear photos. Note any distinuishing markings or behaviors. Offer a reward, if you can, but DO NOT post how much the reward is. Be sure to note on the flyer if your dog is on any medications or needs regular veterinary care. Get at least 200 flyers to start with, and post them where ever people will gather and have the chance to see them.
Kids are great at spotting dogs.
This helps keep public relations on a positive note for the next person who may want to post a flyer, and may mean that your flyer stays up a bit longer. Keep rechecking where you have posted them and post again if necessary. Keep a supply of flyers in your car, and give one to other dog lovers you happen to run across. Give them to anyone with a dog in their car, especially if that person has the same breed as yours. Dog lovers are happy to help keep an eye out for a lost or stolen dog.