I recently adopted a 2 year old from a shelter and he's been a handful but surprisingly a good dog. I don't know his circumstances before he was found and sheltered but right away I just let him know we can be trusted, we shower him with treats and he learned basic commands within the 1st few days, (sit, lay down, stop, fetch) because he often gets treats whenever he listens to us. I take him for walks daily because he is a high energy dog that absolutely needs daily exercise/running, (he's a collie mix), so we run him around the yard for 15 or so minutes than after that's when we take him for a walk so that he's not going crazy and pulling when we do go for the walk, because he's already half tired from the running around. I mean take it day by day, every day is a new day where you'll learn something new about your dog, and instinctively you'll know what you need to do to train your dog. Every dog is different. Good luck!