Hi, I did have this problem and I still do to a certain degree particularly when talking to people in large groups. I think the most important thing to remember is try and be yourself! I know this sounds cliche but when I was younger I used to almost put on a mask and pretended to be something that I was not which I could not live up to. In reality I am shy but will be much more outgoing once when I get to know somebody better. I would just try and talk to people about common interests, if you like drama and stuff, maybe ask them whether they like going to see plays, what plays they like, or talk about music anything which can start off a conversation. Try and keep eye contact I know this may be kind of difficult I detest eye contact and avoid it when possible but reassuring lances of eye contact will show that you are interested in the conversation and should hopefully keep it flowing.
I hope these tips help, good luck megscullen97