In the 1980s veterinarian and animal behaviourist Ian Dunbar discovered that despite evidence on the peak learning periods in animals, few dog trainers worked with puppies before they were six months old.[27] Dunbar founded Sirius Dog Training, the first off-leash training program specifically for puppies, which emphasizes the importance of teaching bite inhibition, sociality, and other basic household manners, to dogs under six months of age.[33] Dunbar has written numerous books, and is known for his international seminar presentations and award-winning videos on puppy and dog behavior and training.[34]

There is nothing inherently wrong with telling your dog “no,” except that it doesn’t give him enough information. Instead of telling your dog “no,” tell him what you want him to do. Dogs don’t generalize well, so if your dog jumps up on someone to say hello and you say no, he may jump higher or he may jump to the left side instead of the right. A better alternative would be to ask him to “sit.” Tell him what you want him to do in order to avoid confusion.
Just because your new dog is old enough that he should know where to potty doesn’t mean that he actually does. An adult dog has the necessary muscle control to hold it for longer periods of time, but if no one ever taught him the potty training rules then he’s the equivalent of a brand new puppy. Age should not be equated with housetraining prowess, so it’s a good idea to treat any dog new to your home as if he’s still learning the potty training ropes.
If your dog isn’t giving you an obvious signal that they need to go out (like whining at the door) I suggest teaching them to ring a bell when they need to go outside. Some of the other signs dogs give that they need to go out such as pacing around or circling can be easy to miss if they’re in another room, which is why a noise based signal such as ringing a bell can make things easier.

Motivational training has its roots in captive animal training, where compulsion and corrections are both difficult and dangerous, and ignoring bad behavior is not problematic as the animal lives under controlled conditions. As a dog training strategy, purely positive training is feasible, but difficult, as it requires time and patience to control the rewards the dog receives for behavior. Some activities such as jumping up or chasing squirrels are intrinsically rewarding, the activity is its own reward, and with some activities the environment may provide reinforcement such as when the response from dog next door encourages barking.[61]
In considering the natural behaviours of specific breeds of dogs, it is possible to train them to perform specialised, highly useful, tasks. For example, Labrador retrievers are the favoured breed for the detection of explosives. This is because of a combination of factors including their food drive which enables them to keep focused on a task despite noise and other distractions. Most working breeds of dogs are able to be trained to find people with their sense of smell (as opposed to their sense of sight). Cocker Spaniels are able to be trained as part of a termite detection team. Their relatively small size enables them to fit into small spaces, and their light weight allows them to walk on areas of ceiling which would be dangerous to anything heavier. In fact, although unusual, termite detection dogs are much more reliable at detecting termites than humans who rely on a basic system of tapping and listening. Because of their ability to learn signals by sight and for their energetic and athletic natures, German Shepherds are able to be trained for work alongside search and rescue teams and human apprehension teams.[83]

^ Herron, Meghan E.; Shofer, Frances S.; Reisner, Ilana R. (2009). "Survey of the use and outcome of confrontational and non-confrontational training methods in client-owned dogs showing undesired behaviors" (PDF). Applied Animal Behaviour Science. 117 (1–2): 47–54. doi:10.1016/j.applanim.2008.12.011. ISSN 0168-1591. Archived from the original (PDF) on October 29, 2012.

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.[39] 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.[40] 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.
Before enrolling with a particular club contact them and ask if you can go to watch a class without your dog. This will help you decide if this is the right environment for you and your dog. Some clubs have waiting lists and you will need to book ahead, some accept people on a roll on roll off basis. Prices will vary from a joining fee and then weekly payments to a one off fee for a certain length of training.