…on the new addition!
We wish you & your new dog a lifetime of great friendship!
INTRODUCTION TO YOUR OTHER DOGS
Ideally you want to introduce your new pup to your existing one(s) in a neutral space. Can a friend or family member meet you at the dog park when you bring Fido home? Remember, you may have been planning this but neither your current dogs nor your new dog have had any preparation for this exciting moment. You want to do everything you can to keep it friendly and calm with no dog feeling blindsided, which may get the relationship off on the wrong foot.
IT'S POTTY TIME
When you first get home with Fido on a leash, take him directly to the outside spot where he should eliminate. Praise him highly when he does it, and THEN go inside. Give him lots of opportunities the first several days he's at home to go outside (with you for most of them), and each time he does his business there, let him know that he just did the best thing ever. (If he doesn't need to go when you first get home, you can still go inside but take him out plenty more times soon after arrival.)
A SPOT TO CALL HIS OWN
Dogs need a space of their own where they can feel secure and out of the way but from where they an see everything going on in the house. Especially his first few days in his new home, he'll want to be in a comfortable spot where he can watch and become familiar with the strange activities in his new home… And he'll better understand that it IS his new home if he's got his own comfy place and a little personal space. You might even give him two of his own places inside the house, plus one sheltered outside. Some people have great success with crate training, both for letting the dog feel comfortable AND for potty training. If you use a crate, don't lock your dog in it right away. See resources on how to do it humanely and in a way that your dog will trust you.
PERSONAL SPACE NOW. CUDDLES SOON
It may seem counterintuitive, but dogs do not interact like humans do, especially when it comes to eye contact and touch, and especially if they don't know you yet. For the first few days at home, the more you (1) avoid looking directly into your new dog's eyes, and (2) refrain from reaching your hand to his head, he will start trusting you A LOT faster than if you ogle him and keep touching him (even if you adore him!) It's very hard to do if you just absolutely love your new pup, but it DEFINITELY pays off very quickly if you can recognize when he's a little bit anxious and keep your hands and eyes off him out of respect during those times. You can still keep him with you, take him for walks, play with him, coo to him and love him, all the good stuff, but it pays to be mindful of his personal space needs right off the bat. If he's clearly affectionate and asking you to be pet, of course, do it! But understand too that a dog on his back showing you his belly is usually showing fear & submission, and is better given a little space at first.
Even when it's going GREAT right away, you don't want to leave your new dog unsupervised with kids or other animals for the first four days. That's about the time it takes for your dog's true personality to begin to emerge, and enough time to see how the new dog gets along with other personalities in the home (human & otherwise).
PLAY, EXERCISE, TRAIN (PET)
Good dogs become great dogs when they're stimulated both physically and mentally. Play with your dog (probably you want to without being told!) and he'll think you're just the best. Exercise your dog and he'll be healthy and calm (and he'll think you're just the best). Reward your dog with tasty treats for doing things you want him to do (sitting, lying down, staying, high-fiving), and he'll do it again — that's training, and it can be a lot of fun for both of you! There are good resources about positive reinforcement training, which is the best kind because it's by far the most effective. (Avoid punishment-based training… It not only scares your dog and prevents him from trusting you, it doesn't work nearly as well.)