liquidreality,
I have suffered through periods of great social anxiety throughout my teens and young adulthood. Since then I've mostly been on an upward spiral. Recently I've had a few periods where I feel I've completely conquered the problem, I'm as comfortable as I can be with myself and others. Of course this is not true and at times I find the anxiety creeping back. Still, today, I'm miles away from where I was in my mid-teens.
Personally I have found that the root cause of my Social Anxiety was not being comfortable with myself. With tunnel-vision I would focus in on everything I was doing wrong, things and tendencies that made me different. I was rarely 'myself' around people other than my closest childhood friend. Situations involving possible rejection were incredibly difficult for me to handle (especially regarding friendships and relationships).
Later down the path, in my young adulthood, I made a pretty drastic change in my lifestyle. I met a lot of people that became important in my life. They were open-minded, real, and very empathetic. I went through some huge identity changes, kinda flopped out for a while and started partying hard, also did a lot of psychedelic exploring. During this phase, for the first time in my life, I felt like I had finally grown into my skin. Most of my social anxiety had been left behind with everything else I ditched. I felt comfortable. More than comfortable, I loved me. LSD also had a huge role, by motivating me to dig deeper and find the insight I was searching for.
The single most important thing in my solution was my friends. Having real, upfront, earnest, loving, understanding, and appreciative friends, with whom you don't feel uncomfortable being yourself around, is better than any drug. I found that having a group of people like this (however you need to find that, be it: clubs, sports, parties, raves, bands, etc) and opening up to them was the single greatest step in overcoming my social phobia.
Whatever you need to do in order to strengthen your love of self, do it. Test yourself, try to force some risk-taking on yourself, not focusing as much on the outcome as the experience. When rejection comes (as it will), try to laugh, brush it off, and tell yourself "practice makes perfect".
Anyways, getting a bit loopy by now. I'm sure you've already thought about much of this, but I just thought I'd bring my experience to the table in case you or someone else could gain something from it. I understand completely that to overcome this condition you have to find your own solution, through your own experience. No amount of words / stories / advice will fix you although it can be a good source of motivation.
Hopefully that didn't come out too scatter-brained for anyone to read. I sincerely wish you the best of luck, though I don't think you'll need it. I think you'll be just fine. It may take time, but luckily we have plenty of that. Remember its all mental and can always be dealt with.