If you buy a puppy, make sure you buy from a reputable breeder and ideally get to meet your pup’s parents! Get in writing what vaccinations etc your pup might have already got.
Ask for a small amount of the normal food they have already been feeding it. Then you can gradually change over to the good quality puppy food you may have already bought. You will also need bowls for food and water, a dog bed, a brush and a collar and lead.
When your new dog arrives, be gentle and patient while he settles in. Give him space and don’t expect perfect behaviour from the start. But do stick to a routine so he knows he will get regular food, walks and play!