You should always accompany your puppy outside for potty breaks. You’re there not only to ensure that he actually goes, you’re also there to reward your puppy with a treat for going in the proper spot. Wait until your puppy finishes eliminating and immediately give him a tasty reward for a job well done. If you wait until you get back in the house, your puppy won’t make the connection between his elimination and the reward.
Operant conditioning (or instrumental conditioning) is a form of learning in which an individual's behavior is modified by its consequences. Two complementary motivations drive instrumental learning: the maximization of positive outcomes and minimization of aversive ones. There are two ways in which behavior is reinforced or strengthened: positive reinforcement occurs when a behavior is strengthened by producing some desirable consequence; negative reinforcement occurs when a behavior is strengthened by avoiding some undesirable consequence. There are two ways in which behavior is decreased or weakened: negative punishment occurs when a behavior is weakened by not producing a reinforcing consequence; and positive punishment occurs when a behavior is weakened by producing a consequence that is a disincentive. In combination, these basic reinforcing and punishing contingencies provide four ways for modifying behavior. Reinforcement increases the relative probability or frequency of the behavior it follows, while punishment decreases the relative probability or frequency of the behaviour it follows.
Just so you know, a puppy is never completely housetrained until they are 6 months old. For some breeds, even later. This means that though you may be making tremendous progress housetraining, there will be "mistakes". Sometimes for reasons you can't figure out! Don't fret about it. Stay focused on the progress you are making. Your confidence in the techniques you are using to house train your puppy will ensure your success.
The Monks of New Skete, who were breeders and trainers of German Shepherds in Cambridge, New York, published How to Be Your Dog's Best Friend: A Training Manual for Dog Owners in 1978 and it became an immediate best seller. Despite advocating a philosophy that "understanding is the key to communication and compassion with your dog," they endorsed confrontational punishments which were later shown to elicit dangerously aggressive responses in many dogs.
Remember that training is an ongoing process. You will never be completely finished. It is important to keep working on obedience training throughout the life of your dog. People who learn a language at a young age but stop speaking that language may forget much of it as they grow older. The same goes for your dog: use it or lose it. Running through even the most basic tricks and commands will help them stay fresh in your dog's mind. Plus, it's a great way to spend time with your dog.