Take an article of clothing that you wear a lot, the longer you wear it the better so your dog can pick up the scent.
Bring it to wherever you last saw your dog and leave it there.
If your dog has a crate bring it there too.
Leave some of his or her favorite toys as well. Also leave a note asking people not to take the items away.
Bring a bowl of clean water since your dog probably won’t have access while out in the open.
DON’T leave food out though, it is likely to attract other animals that you’re dog will probably want to avoid.
Come back as often as you can to check for your furry friend.