I've never had a dog, but DH wants one. If I wanted to get one, I wouldn't know where to start. I've just googled "puppies for sale" which I'm sure will lead me straight to a load of puppy farms. But they look fine - I wouldn't be able to tell at first glance there's anything wrong.
When you want "a dog", the first step is surely to ask yourself "what sort?". If you don't know, narrow it down a bit: what size, what exercise needs, what sort of temperament, grooming needs etc.
I knew I didn't want a big dog, but I wanted a dog with some spirit and attitude, so that meant terriers. I wanted a wire-haired breed, as they don't really moult. I went to a couple of dog shows and checked out all sorts of terriers. I felt that Scottish, Sealyham, West Highland, Glen of Imaal etc were a bit small, I wanted something leggier.
I've always been very taken with wire-haired fox terriers, but a friend had recently lost his two in quick succession and was broken hearted, and I opted not to get one in case it made him miss his even more. So I considered Welsh terriers (ruled out as there was a health issue in the breed at the time), border terriers (ruled out by my then husband, on the grounds that they look "pugnacious" - twat), but could find no negatives, at least from my point of view, with the lakeland terrier, so that's I got. And I had them for 23 years altogether, and they suited me very well.
Now I'm too old for a breed that can walk 15 miles a day without a second thought and needs at least 3 miles a day, I'm looking to get a whippet from a rescue. I'd have a rescue greyhound if I had the space, but my house is small and greyhounds don't curl up.
So work out what you want in a dog, what is manageable in terms of size and grooming, and what is practical. That should narrow things down a lot. Read up on the breeds you like the look of, especially temperament, health and exercise needs. Go to some dog shows (the dates for championship shows will be online, try Fosse Data or Higham Press), look at the breeds, talk to the breeders. And there must be loads of groups on FB for specific breeds. Contact the breed club. But most of all, when you go to choose one, have a good look at how they're kept.