GAME - Just ONE thing

Get pet insurance...it saved us thousands!!!!

Before leaving it alone in a room, make sure there's nothing it could destroy, and (durable) toys are good if it knows its supposed to play with those and not your clothes/shoes/furniture.

Brush puppy from day one so it gets use to grooming and touch the puppy all over when doing this so as the pup grows up anyone can touch your pup anywhere if needed vet, groomer, you.

puppies cost MONEY - not just the adoption fee, or purchasing price. There are vet bills, surgical needs (spay/neuter), toys, food, treats, all sorts of things. Be prepared to spend, and not just on the cutesy stuff. 

to play off Amanda's...

Teach your GIANT breed, to "UP" or help you to lift it by putting it's front half up...or to use a ramp. BOTH will come in handy because most Giant's cannot be lifted completely off the ground, by most owners beyond the first year.

Do not get a pup younger than 8 weeks old; 10-12 weeks old is even better because pups need to learn doggie manners from their mama and learn bite inhibition interacting with their siblings.

Socialize, socialize, and socialize some more.

The Puppies Rule of Twelve

The primary socialization period ends at 12 weeks; the secondary period at 16 weeks.  Socialization should continue after that, but is most effective in the first 16 weeks.

Unless you are showing, spay or neuter.

 Vet visit immediately to ensure good health!

 Get the puppy used to having its nails done and its teeth brushed. A few minutes of practice once or twice a week will make your life MUCH easier when the puppy gets bigger!

Teaching the pup what TO DO rather than what NOT to do is kinder and more effective by far. 

Simple.

Constant Supervision.

Introduce all new foods slowly