Do you currently have pets? How will a puppy fit into your existing home if you do have other pets?
What will you do with the dog if you move from your present home?
Do all members of the household know you plan to get a dog? Are they all agreeable?
What previous experiences do you have in training a household pet? (housebreaking, basic obedience, etc.)
What training methods will you use to handle potential problems like whining, barking, chewing, etc.?
Who will be responsible for the care of this dog? What happens if he/she doesn't follow through?
Are you willing to obtain proper medical care for this dog, such as yearly boosters, cleaning teeth, etc.? The expense of a dog does not end when you buy the dog. The price you pay is a small price compared to the lifetime of a dog.
Is anyone in your household allergic to pets?
Will an adult be home most days? If you work, what is your plan for caring for a young puppy during the day? (Example - plan on coming home during lunch to let the puppy out, or have a neighbor do it, or keep confined to a bathroom with newspaper down, etc.)
What will you do with this dog when you go on vacation?
Will the full grown size of the dog be an issue for you? A cute 10 pound puppy is adorable, but when that puppy turns into a 90 pound ball of energy, how will you handle this?