I'd recommend carefully researching what breeds are compatible with you and your lifestyle, including mixed breeds. Some dogs might be okay on their own but it's my understanding that most need some socialization and activity/stimulation during the day.

If you can't be at home for extended periods of time, I would hire a dogwalker or make sure a friend can spend time with that dog, and/or bring it to a dog park to socialize with other dogs.

If none of that works for you, and I don't mean this dismissively, but you might want to consider getting a cat instead.