Decide in advance which family member will be responsible for duties such as walking the dog, feeding, bathing, etc. Dogs are social animals and do not respond well to being isolated from the family. They should be a family member, not a possession that is kept on a chain in the back yard. There is no simple answer to that question. When choosing a breed of dog, again consider your lifestyle.
Some breeds require more exercise time, grooming care, etc.
Long-haired breeds such as the Afghan, the Yorkie, and the Collie require a significant amount of time to care for their haircoat. Take into account your family's residence. If you live in a studio apartment on the 17th floor, then the Mastiff is quite likely not for you. On the other hand, if you live on a farm and want a dog to help herd sheep and cattle, the Chihuahua is not a good choice. Keep in mind some of the advantages of owning a mixed-breed dog.