The first thing you need to do is decide on what breed(s) and/or mix(es) you are interested in, and that would fit with your lifestyle and tastes. For example, retired racing Greyhounds can make fantastic apartment dogs, but if you don't want a 50-ish pound dog, they they aren't for you. Conversely, a lot of smaller dogs, like a Parson Russel Terrier or the like, while being smaller, require a lot of physical and mental stimulation, which can make then lousy apartment dogs. Seriously... my brother had to give his Italian Greyhound to our mother because he was about to be kicked out of his apartment over the dog barking so much, yet his Great Pyrenees was an extremely calm, quiet dog that the neighbors didn't mind.
So, first things first: What is your previous experience with dogs? What size dog do you want? How much exercise are you (realistically) willing to give your dog? How much time, effort, and money are you (again, realistically) willing to put into grooming? Are there any size/breed restrictions imposed by your landlord? Are there any BSL restrictions where you live (BSL is stupid and useless, but still something you need to consider)?
Another thing to consider is that puppies take a lot. A lot of time. A lot of energy. A lot of training. A lot of tearing your hair out, wondering what in the heck you've gotten yourself into. Getting an adult dog will usually put you ahead of the game when it comes to things like house training and chewing.
