Walk into a room assuming that everyone already likes you.
Body language! Check out the direction people’s feet are facing. If they are pointing at you, they are engaged by your conversation. If just their upper body is facing you but not their feet, then they are just being polite.
Everyone likes a good listener. If you ask someone a question (especially about themselves), they might give you a curt answer. Remain quiet and keep eye contact and they will most likely continue.