You should start your search at your home. Quietly walk and drive around the area. Take a leash, a bag of food (hot dogs, Vienna sausages) as bait. Favorite toys are good, especially if the dog goes absolutely bonkers when he/she sees it. Talk briefly with anyone you see; ask if they saw your dog.
Make sure you search your own property first and then the surrounding neighbor's property, checking areas where your dog could be trapped, injured, or deceased. Dogs have become trapped inside sheds, closed inside trailers, entangled in wires under homes, dropped into wells, and even fallen into neighboring swimming pools.
In the winter, check for evidence of a disturbed pool cover. If you live near the water, please check under boat docks. Accidents happen and he or she could be trapped underneath. (Reminder: never go on private property without permission)