You know how people say first impression doesn’t mean anything? Well that is a lie. During the first impression you usually see true person for who they are. Don’t get me wrong here you can’t find everything out from the first impression but if you pay attention you can learn a lot.
For example: The longer you talk to this person the more they learn about you. Soon enough they will know how to avoid the things you don’t like and will bring up the things you do like so the conversation is pleasing.
Your best bet it to be forward with the person at first and find out what they are like so you can get a good idea on who they are and if you like them or not. What I mean by this is don’t be boring, bring up a lot of subjects on different things. And try not to be a hard ass or cocky because this makes most people mad or annoyed then of course they won’t want to talk to you. (This also works really good if someone is trying to lie to you it will quickly flush them out.) This will give you a quick insight on who this person is. Although to truly know them you will have to be their friend for a while and build trust before you truly know the person for whom they are.
If you need any more info just reply to this thread and I will see what I can help you with.