"Practise becoming fascinated by other people. Ask them about themselves, and concentrate when they answer you. Remember what they tell you about themselves so you can talk about it later, or on another occasion.
Great socialisers make other people feel comfortable and interesting. How do they do that? By being really, genuinely interested in other people. If you are talking to someone and you feel boring or inferior, ask why that is. Is it really all your fault?
Practise using fewer 'personal pronouns' when you talk about things. Sentences beginning with 'I' are not only a turn-off for the listener, they also keep the focus of attention on you, which increases shyness. (Note: Of course, part of friendship is giving away things about yourself, but only when you feel it is appropriate to do so.)
Remember that the way to overcome shyness is to focus elsewhere. Like on imagining what it will be like to really enjoy the social event, on how it will feel to be full of energy, or to be having a great conversation with someone. "
One exercise involves you switching focus from one task to another. For example, set a timer for 5 min. After it reaches 0, stop whatever you are doing and switch to something else. Do that for another 5 min, after which you can return to the first task or do something else altogether. This is supposed to help build control over focus, so that you have an easier time projecting it outwards in a social situation.
Hope this helps you.