Beginning at the beginning seems the most logical … so let's begin with deciding if we can give a puppy [and the resultant fully-grown dog] a good and loving home.
NB: If you are a seasoned dog owner, you will probably want to miss this section out.
Once you have established that you will be available for a good part of 24/7, and 52 weeks per year for your pet … and if not personally available, then you have 'baby-sitting' facilities available for your pet .. Then we can go on to what sort of home you can provide.
This is where breed research will come into its own. If you decide you want a particular breed, find out as much as possible of what facilities, exercise, etcetera, your pet will require … and find out if that matches up with what you can offer.
A couple, or three, examples!
First think long haired / short haired, color, are you too houseproud? Some dogs shed their coats more than others. Grooming as a routine is a daily 'must' if you take on a long haired breed.
If you go for a working breed, like a sheepdog, remember they NEED loads of exercise, and something of interest to do … like agility or flyball, or they can become problem dogs [have you got the time and energy to look after Them properly]?
You would think that a retired grayhound would require loads of exercise … no, they just need loads of love and a couple of walks a day!
Large dog, large garden? No, not necessarily, a Ridgeback would have much better a large sofa!
So most important is to choose the right type / breed of puppy, both for your lifestyle and circumstances, and for what type of lifestyle you can give your pet.
Once you have researched this thoroughly and honestly, then it is time to find a reputable breeder, and to form a relationship with them and learn all you can about the dam and sire of the puppies … they may also be able to help you Decide on whether you want a male or female pup.
Always remember it is wise to choose a pup which is 'somewhere in the middle' within the hierarchy of the family of pups. [The litter 'boss' will be hardest to train … they will be unwilling to give up their role as 'top dog' to you. The runt of the litter may have as yet unknown health problems … your heart could easily be broken!]
A pup from the middle of the hierarchy should turn out to be both healthy and willing to learn … biddable. When you look at the pups they should have clear eyes, shiny coat, and once they reach the 8 week stage, should be lively and inquisitive.