When I am getting to know someone, I don't assume anything about their behaviour and the way they are. I treat them as they are: a unique individual. I learn their ways and what works for them. I don't assume they are going to be a certain way, just because most other people are.
Based on my own experiences, there has often been an assumption that I am going to behave and like the same sorts of things that other people like, before I've even been given a chance to say otherwise. Sometimes I will explicitly tell a person(s) something important or specific about me, and I'm always very surprised when they seemingly 'forget' this information...