If you have to deal with this problem or have dealt with it in the past, I just thought it might be nice to share strategies that helped you along the way. I have a few:
-Script yourself: Y'know how people who work in retail have scripts? They don't have to react to each customer as an individual if they don't want to, they can just follow their script: "Hello, welcome to [blank], how can I help you; thank you, have a nice day!"
You can use that to ease social interactions by deciding in advance what you're going to say when they begin. Many years ago, I decided that my response to "Hello, how are you" would be "Fine, thanks". Just two words, but you wouldn't believe how much they've helped. Just the ability to give a confident, immediate answer to a common greeting does wonders for your self-esteem. ^^
-Renew your wardrobe: I saw a TED video on this a few weeks ago, and although the presenter was a bit exaggerated for my taste, I found that I completely agreed with her message: Clothes are silent self-expression, and you can use them to tell people who you are without having to say a word. You'll feel much more confident in clothes that you actually like, that reflect the person you really are.
A lot of my progress correlated with my increasing ability to buy my own clothes, and I don't think that was just coincidence. I love experimenting on myself with new styles, and I find that the more dramatic I get, the more dramatic I want to be.
Last year I bought a pair of fishnet gloves for Halloween, and the other day I wore them outside again, just for fun. It was a great day~. I don't think anyone else even noticed I had them on, but I did, and they made me feel so...individual and powerful. I loved the way they looked on my hands, and the fact that I could wear something unconventional and just enjoy it for myself felt freeing.
I want to keep getting crazier~. Sometimes I imagine walking down the street in costume armor or a flowing cape, and it makes me laugh, but, if it could make me feel as good as those little gloves did, why shouldn't I try it?
Don't worry about what other people might think; wear what'll make you happy. You may find that attitude spreading to the rest of your personality. ;]