Get bitter apple spray for chewing and handle paws, teeth, gums, belly, tail when young. My dog is defensive when nail clipping and it is obnoxious. Keep high value treats on hand and start training as early as you can.

That’s what I wish I did when my dog was a puppy.

Veterinarian here and my answer would depend on your housing situation and the breed of dog you're getting. Like if you're getting a small toy breed and you live in an apartment maybe get some pee pads ready and start brushing teeth as young as possible..

Most universal recommendations would probably be small dehydrated liver bits for training in a tightly sealed bag you take with you wherever you go. Almost everything else can be situational. For difficult large breeds with prey drive that live on property I see a lot of success with e-collars / training collars instead of a leash. Don't want your pet to think every chance off a leash is a chance to escape and be free.

A good start for you:

-pee pads -microchipping -vet check up -adjustable food station to raise up higher with age -dog bed -blanket -wash wipes -dog shampoo -wash helping brush -dog towel -walking harness -leash -collar -nail cutters -hair brushes for their hair length -puppy food and treats

Get a crate and don't call yourself a puppy parent.