Your best bet is to talk to a professional, like a vet or some other person who regularly takes care of cats as a profession. They tend to know all about the differences between breeds, what each needs, and what you should do.
Also, the internets are quite useful.
All the cats I have ever had were adopted and not bought. My first cat, who still lives with me to this day (he is fourteen) was adopted from a tiny zoo/animal house that is not very far, he had no real home and we took him in. One cat which was with us for only a few weeks was stuck on a tree and freed by my sister. The third, who is still here as well, was stuck under the car, I think.
The breed of the first is Balenese (maybe cross-bred), and he is very calm and rarely irritated. When he is, he occasionally smacks the responsible person, but only if necessary. He commands enough respect that our dog, a full-size Australian Shepard (a large, very energetic breed) dares not come too close.
The breed of the third is a Munchkin cross-bred with something else. He is very playful, when in the mood, and quite cute, but is very phobic, fearing things such as balloons, getting picked up, and having his food taken away. He is very energetic, perhaps due to his young age.
If I were you, I would adopt a cat from the street of animal shelter, as it does better for the cat that you could do to a pampered bought cat. You need to take the cat to a vet, though, and learn about raising cats.
I can tell you more about these breeds, or what I know of them, if you like.
Good luck!