we have a springer spaniel. (which I am not recommending by the way, just saying)
he was a rescue dog.
We had dogs when i was a kid, and didn't really expect to get a dog now. We started by dog sitting my cousin's dog a lot when he needed to go and support his elderly dad.
They we dog sat my friends (incredibly well behaved lab) when they were on holiday, and my son walked him for pocket money sometimes too.
Then we fostered for the local dog rescue, and our 4th foster was the springer who kind of stayed.
It is great to rescue a dog, but to be honest you don't sound as if you know much about dogs. That's fine, we all have to start somewhere. I suggest you get to know someone with a dog and offer to walk with them, or dog sit for them and learn a bit more about what sort of dog you like.
For example, my cousins dog is a Golden retriever, he is a lovely character but HUGE and takes up the whole living room floor.
I was smitten by the nice character of my friend's lab. Then their old lab died and they got a new puppy and we dog sat for them a few times, he taught us how he was training the puppy, and it was eye opening, we discovered why his old lab was so well behaved, the hours of good training he had put in.
We learnt so much from these dogs and their owners and the owner of the dog rescue when we were fostering. I don't think we would have been a successful placement for our current dog without all of that.