As many have said before me, being genuine and true to yourself helps. However try to read someone and see how they act around you, small tips can go a long way in identifying what they feel comfortable with. Don't start conversations with over saturation or inappropriate topics; that'll sink you fast. Instead focus on asking them how they're day was and listening to them, people will tell you a lot about them if you let them and that'll open a door for conversation. Of course be aware that some people don't like talking about themselves and they may end up feeling worse off so try to read their confidence in that.