cat owners!! tell interested buyers what they NEED to know before adopting

i myself, an interested buyer. am unsure about how to treat a cat when i adopt it. i’m worried about making mistakes when bringing home a new cat. I want to make sure I build trust from the beginning and don’t accidentally make the cat feel unsafe.
please read the text below!

i’m think of buying a cat. me and my sister have decided it will be a ragdoll, siamise, or british shorthair. but i’m still not so sure about how i’m supposed to treat the cat when we adopt one! the sterotypes are obvious; independent, not so social, shy, hard to warm up. but i want to know, is this something i should follow? or is there anything else that’s more important to know? also, how much would it cost to vaccinate the cat? we plan on buying one.