I honestly cannot make friends I need help

Ok so I don't really talk to anyone in sixth form
Well I do butthe thing is when I make friends it is ok but then they start to get really mean towards me an cal me weird if I smile or especially when I make jokes and they always against whatever I say

So that's I consider it as me not having friends because i'm really unhappy my ""friends"are 2faced and i'm planning on not speaking to them anymore once I start university this year. I barely speak now oreeven hang with them out side of colleg

So because of my situation and how down I feel... I can't remember how I am around new people and from the bottom of my heart I don't know how to be

So how should I act like say when I meet new people (planning to do this an open day thing)..when I go uni I will meet new people and would like to be friends
But I have no idea what to say!!

I honestly can't have a conversation anymore because I over think things
So please how should I behave to not be annoyi
How can I interact.. I am quiet shy at first so idk how to spark conversations


Usually outgoing people have loads of friends so I can't pretend to be loud because i'm just a loner

Please respond