Most people buy a puppy because they like the way it looks, irrespective of what its adult motivations will be or whether they themselves are physically active or whether they live in a traffic filled urban situation or the quiet countryside.
The classic mistakes are the sofa loving person, who lives in a town, buying a Border Collie or a soft, shy, person buying a dog that will be a strong, bigger than expected Guardian dog that will, without understanding, spend its life barking at whatever movement it sees.
You need to know whether the breed you choose suits your lifestyle, your personality type, your energy levels as well as the all-important factor of the best time to separate the puppy from its mother. Toilet training, the first time on the lead, basic dog language to allow you to communicate.
How to instil all those basics that allow you to live happily together will be covered in every regard up until the puppy is 10 months old.