Some owners enjoy dressing up there pet in fancy jeweled collars, there is nothing wrong with this, but you should always try to avoid dangling ornaments that can gat caught, trapping the animal and could cause injury. A properly fitted collar is tight enough so that it is unable to slip over the dogs head, while still loose enough to offer no constriction. You should be able to slip two adult fingers between the collar and neck of an adult dog. A puppy will grow so fast that his first collar must allow plenty of room for expansion. You should purchase one with several holes, start with the last one (loosest), and adjust it comfortably each time you put it on him.
An essential safety feature which all dog collars should provide is the identity tag. The best kind is an engraved name and address plaque permanently attached to the collar. Some very small collars do not have room for this, so smaller pets have to wear a round engraved medal attached to the collar. The pets name and the owners phone number should always be on the tag, and many counties require that immunization tags be worn with current records. Above all else, a collar should be chosen for its comfort first and foremost, with style and look always a secondary consideration.