Puppies will grow -  The most important thing to remember is that a puppy WILL grow.  While a 10 lb puppy is cute and cuddly, this same puppy might grow to be an 80lb adult dog.  When a puppy comes home with you, his life is in your hands.  If you miscalculate how big he'll become, he may end up in a shelter with countless other puppies-turned-too-bog-adults whose only crime it that he grew too big.

Time Commitment - puppies need 24/7 care and attention.  It's much like raising a child.  Puppies cannot control their biological urges.  Puppies must be taken outside at least every 3-4 hours in order to establish a housetraining routine.  Are you able to take the puppy out every 3-4 hours?  Don't count on the adage that "dogs will not mess in their den."  Since a puppy cannot control it's urges, any accidents in the house will set back housetraining efforts tenfold. Don't rely on a crate to housebreak a pup!!!

Puppies chew! - chewing is a natural behavior in most dogs up until the age of two.  Consider potential destruction of carpets or prized possessions.  Punishing a puppy for chewing will backfire and the puppy will associate the punishment with you rather than the act of chewing.  While chewing is a natural behavior, you can learn how to re-direct some of the chewing behavior by attending a positive reinforcement obedience class or consulting with a trained dog behaviorist.  Chewing is followed by other "natural behaviors" that will test your patience through adolescence - the puppy version of the terrible twos.  Most dogs take a full 18-24 months to fully get past the puppy stage - are you willing to give 2 years to working through these behaviors?

Obedience Training - all puppies will need training in order to modify or redirect "natural puppy behaviors" or to learn how to act appropriately around the house, other people and dogs.  Failure to teach your puppy the things that make him welcome in the family and among the public will likely cause a surrender of the puppy / dog to a shelter.  Bad behavior is one of the top reasons that people surrender dogs at animal shelters.  The puppies / dogs have usually not been trained properly or their owners have not spent adequate time with them.  Are you willing or able to enlist in group obedience class that will help your puppy become a "good citizen?"  Are you willing to spend at least an hour in the morning, early afternoon, late afternoon, and early evening with you puppy?  This will ensure that the puppy is getting the training and attention that he needs at this early age.  If not, you are doing the puppy an injustice.  It may be best to adopt an older dog or wait until you have more time

Socialization - a puppy has a very small "window of opportunity" in which they are open to new experiences.  This period is generally from the age of 5 weeks to 2 months.  If a puppy has not been socialized to various stimuli during this time frame, the pup will develop innate fears of that stimuli.  For example, if a puppy has not had a good experience with small children during this time frame, he will likely develop fears of small children.  The same can be said of "men in hats," "men in uniform," "other dogs," "crowds," etc.  Are you committed to socialize your puppy to every stimuli that you think will come into your puppy's entire life?  This is a major component of raising a puppy.  Most behavior problems, including aggression, are created as a result of the lack of socialization when a puppy is young.  These very behavior problems are often the reason that dogs are surrendered to shelter and county pounds, often costing the puppy's life.  Other shelters may spend valuable resources to rehabilitate a dog with a lack of socialization skills.

Financial Considerations - you will need to pay for a series of vaccines every three to four weeks, fecal examinations (because a large number of puppies have internal parasites), and preventative treatments for heartworm and fleas.  Also it is imperative that you plan for expenses related to spay and neuter surgery.