Collars are important because you usually have identification tags attached to them. The information is vital in case your dog gets lost. The I.D. should have your dog’s name and your name and phone number on it. Following are other tips on dog collars:

Find the Right Collar:  The most common type is a buckle collar. It’s ideal for small pets like cats and small dogs. If your pet is active, and you have difficulty restraining him, a breakaway collar is a good option. For training purposes, a training collar is another choice. Talk to your veterinarian for the best collar for your pet.

Find the Right Size: Most collars are adjustable. It’s important to select a collar that is sized just right for your pet. Measure your pet’s neck with a tape measure. Once the collar is around his neck, make sure you can comfortably slip three to four fingers in between the collar and his neck. You don’t want the collar to be tight. You can also ask your pet store owner to help you with the fit. Some pet stores will custom order large and small size collars for your pet.

Find the Right Style: There are so many designs to choose from—from frilly to plain to fashionable.

Choose the Right Materials: Collars are made from leather, canvas, plastic, and metal. For those of you in hot climes, canvas is a good option because it’s cooler than leather and lets the skin breathe more easily.  Make sure the material is durable.

Don’t Add a Lot of Extras on the Collar: I hate bells on cat collars. I just think I wouldn’t want to hear a bell ringing all day long. I also make sure that any attachments—like I.D. tags—are securely attached and cannot be swallowed.

 Link: http://www.petnewsandviews.com/2009/12/04/5-tips-on-finding-the-right-collar-for-your-pet.aspx