I used to be incredibly shy, well still am, but I've learned how to deal with it better as I got older. As a teenager I was very socially awkward. And social situations and small talk was something that sent me into a panic. But life has to go on and I put myself more and more outside my comfort zone. Its not an overnight thing but some things which helped me are:
If I was to be in a situation where I knew very few people and knew I had to socialise I would actually jot down some topics before going out that I could talk about if needed. Just general stuff. I started with the weather, just something like 'its been so hot today!' and then usually someone would respond with something I could join in with. I wasn't the least bit interested in the weather but it was an easier one.
Other things could be (depnding on whether social or work related) 'what do you do for work?', 'Are you here with your family/friends', 'How far have you had to come today', 'I love your jumper (or anything), I've been looking for similar where did you get it'
Just take a bit of time before you go out and jot down some things relevant to where you are going.
In terms of body language. If you feel awkwards, try and have something in your hands. A drink, a pen and paper, jumper, anything, you won;'t feel as 'exposed' and may relax a little as you won't need to start wondering what to do with your hands. When people are talking, look at them. It may feel odd to start with if you're not used to it, but it gets easier. They won't think you're weird for looking at them when they speak. It shows interest.
Practice a few reasons for leaving a convo - just getting a drink, just need to grab something from the car, things like that.
if you are talking and there are awkward silences, perhaps both of you are unsure what to say next. Say something like, I never know what to say at these things, or refer to some of your pre thought out q's from above.
Theres no magical solution, except pushing yourself right outside your comfort zone and keeping going. It will become easier. Practice makes perfect as they say. If you feel panicked or awkward, go to the loo for a few minutes or outside to gather yourself.
And most of all, turn up looking clean and smart and tell yourself before you go out that you look great and you are every bit as valid as anyone else there.