First, I would recommend if you already have not is have the vet check over the dog and get all the shots it needs.
If it is messed up and needs flea treatment, get it from the vet.
If your dog is the type that needs grooming, start it right away. I have two dogs that get groomed. One dog is old and still hates it. Some dogs have hair growing in their ears that need pulled out and the groomer can do that. Some dogs have so much hair, they get matted at their butts and can't poo.
I would NOT feed your dog the cheapest dog food. Another question for the vet to see what the recommend. Or at least do an internet search for the best dog food for your pet. Good food will keep your dog healthy for years to come. Do not feed it chicken bones or most bones due to them getting it caught in their throat. I saved a strange dog from choking one time due to a chicken bone caught in its throat. Make sure their water is clean every day. If it is dirty, clean it twice a day. Dogs get sick from dirty things too.
Dogs like regularity like being fed at the same time every day. My dogs will notice anything out of place and bark if they see something moved.
Always keep your dog on a leash, or in a gated yard and never left alone in a hot car.
They liked to be talked to and learn a vocabulary over time. Water, leash, car, ride, let's go, come, up (stairs), down (quit jumping), dinner, eat, go to bed, get the ball, fetch, NO. Tell them they are good boys or girls.
Socialize your dog around people and other dogs. My dogs were not socialized and we have no family or few visitors and my one dog is very aggressive towards strangers. Very bad indeed.
Both my dogs are old and one who is almost 11 years old has cancer and we have him on a million meds and he goes to the vet a lot, he also had chemo treatments. The other dog is 15 1/2 and has recently developed a minor kidney issue. He is on special Vet dog food for kidney disorders but takes no meds. The other one is also on special vet food for weight maintenance. Very expensive. Before they were on this special dog food they were always fed really good dog foods.
Good luck with your new dog!