You pet should be wearing a flat collar (not a choke collar) with identification tags that have your current phone number. Consider having your cell phone number on the id tag. This way you can take your cell phone with you when you are looking for your animal and avoid missing a call that gives you a current location of your pet. Add "REWARD" on your id tag!
Because collars and tags can tear or slip off, you may also want to consider having your pet microchipped. A microchip is a tiny computer chip, about the size of a grain of rice, that is injected just under your pet's skin, between the shoulder blades. A unique ID number on the microchip is entered into a database along with a description of your pet and your contact information. If your pet is found, animal pounds, vet clinics and rescue organizations can use a microchip reader to read the unique ID number contained on the chip and check the database to get your contact information. The chip can't be lost or damaged, and it lasts for the pet's lifetime. However, it is your responsibility as the pet owner to update your contact information as needed. Most veterinary clinics, as well as the FM Humane Society, provide microchipping services. It is recommended that your pet's microchip be scanned during yearly veterinary exams to make sure that the chip has not migrated.
Make sure there are no potential escape routes and that gates are securely closed. During winter months make sure that snow banks do not form that would allow your pet to easily jump over the fence.
Besides being illegal, it is unsafe!
Both male and female animals will be much less likely to wander if they are "fixed". Additionally there are many health benefits to spay/neutering your pet.
Have ready a current picture of your pet to be used for advertising your lost pet.