Most people think buying a dog would be great, but have you really thought through what it would mean? Most dogs live for over 10 years, so you need to commit to look after then for that length of time if you get one. Plus you need to make sure you have everything you need to look after the puppy, before you bring it home, otherwise you could end up in a pickle.
Probably the easiest thing to buy is food, they are going to need an awful lot of food and nutrients to mature into an adult, so make sure you gets lots of it ready. There are actually different types of food you can buy which are aimed specifically at puppies and say they contain the right nutrients to help them grow to be big and healthy, but I am not sure if they are any better than normal food or not.
Another thing you will need is a load of toys. That may seem like something you can buy later, but you will need them to distract your hyperactive puppy so you can get some work done! If you get some toys that can roll then they can spend hours chasing them around and will nicely tire themselves out at the same time too, also toys they can chew are great to stop them chewing anything else around the house.
Your puppy chewing things up can be a real problem, and one common target is the bed which usually ends up in bits by the end of the day, even though they seem to love their bed and sleep in it all the time. One simple solution to that is to buy an indestructible dog bed which will thwart their attempts to rip it apart, or you could get some training for them to stop them before the habit becomes ingrained.
You will also need some grooming supplies to help keep them fit and healthy, like a dog brush and maybe a tooth brush for them too (brushing regularly will help their breath as well as keep their teeth healthy). Plus a book on puppy and adult dog care would be a great investment if you are new to dog ownership, so you can have some guidance on what you need to do and when.
The final, but probably most important thing to do, is to find a vet in your local area who you will take your dog too. Then once you have the puppy take it along for an examination and to find out what shots it need etc..