1.  Never feed your dog chocolate! Not even just a little bit!   It contains a chemical called Theobromide that is fatal to canines.  Unsweetened and Baking chocolate are the most concentrated kinds but even milk chocolate can be deadly depending on the amount.  If your dog accidently ingests any kind of chocolate please  Call your Vet Immediately or Rush Him/Her to the Nearest Vet Clinic! (Chocolate flavored store-bought doggie treats are okay because they aren't really chocolate and are usually made of carob.)
2.  Never allow your puppy (or any age dog) to mouth on you, which means don't let them chew on your hands or feet or pull on your clothes.  You'd be surprised how many otherwise intelligent people make this mistake.  Don't do it.  Just picture your full grown animal jumping on you, yanking on your clothes, or putting his big teeth on you like when he was a small little guy and you thought it was just soooo cute!  Get the picture?  Whether your dog is a big German Sheherd or a smaller Boston terrier, this behavior can be frightening and dangerous.  Instead, whenever your pup starts to mouth - which is a natural instictive thing that they do with other pups but can't be allowed to do with people - hold his muzzle shut in your hands and firmly say in a growly sort of voice "No Bite".  Then hand him a good chew toy or let him tug on a rope bone while you hold the other end.   He should get the idea pretty soon.    
3.  The best advice I can give for housebreaking your dog is to use a crate or pet carrier.  A lot of people think "Oh, I don't like the idea of a cage"  or  "The puppy will hate being confined".   Most dog owners, vets, and nearly all trainers use crates.  It's really no different than an indoor doghouse with a door and is no more harmful than putting your baby in a playpen.   Just put your pup in there when he sleeps, when you are eating, at bedtime, and whenever you are gone from the house or are too busy to watch him.  This not only keeps him from having an accident on the rug, but also keeps him from getting into things and tearing the house apart when you're not able to keep an eye on him.  Take him outside first thing in the morning, after every meal, and last thing at night.  Puppies have to go out every few hours until their bladders get bigger, but by the time your dog is five or six months old they can be put on a schedule where they'll only need to go out 3 or 4 times a day.   And trust me, if you have to clean up an "accident", it is much easier to wipe out a crate than to have to sop pee out of the carpet with a bunch of towels.
4.   Use common sense and try not to put your dog into any situation you wouldn't leave a two-year-old in.  Don't let them run loose where they could get into traffic, don't leave them unattended in a hot car, make sure they have fresh food and water every single day (no matter how tired you happen to be or how late you get in), don't expect them to bring you a lease and bark at the door when they have to go, and, I don't know about you, but I would never, ever, let a two-year-old or one of my dogs have the run of my house while I'm gone.  There's just too much fun, messy stuff for them to get into.
5.  Please, under no circumstances, hit your dog.  That's only going to teach them that you are big and mean and out of control.  Most people who end up getting bitten by their own dogs are owners who like to give a little smack for disobedience.  Please don't.
Important Tips and Facts
Every Dog Owner Should Know