If you've had your dog for a while, then chances are he's grown bored with his daily routine. Spice up his playtime and outdoor runs with a few new tricks, or give him a refresher course of his original training. New tricks will stimulate your pooch's brain and make him sharper, better behaved, and more engaged.
If you have a new dog or one that just won't behave, then sign up for a local training class. Going through a guided training course together will be quality bonding time, and it will give you a sense of accomplishment and your dog brand-new manners!