Hi @Ella welcome!
In my opinion the best way to osa is to learn about it more and more not just in general but exactly how it affects you personally, the more you learn about it more stronger you will feel, research shows that insight is a big motivator, and you know when we are swallowed by sa we are starving for motivation, ya i recall now its also said by Dr Aaron Beck the founding member of cbt. After insight comes behavior. Basically dysfunctional thinking and dysfunctional behavior pattern are the two main components of sa according to cbt, then each of these have their branches for example according to the Clark and Wells model of SA Negative thinking pattern, Excessive Self Consciousness, Safety Behaviors, lack of confidence and fear are the four main components of sa studying each of them carefully and systematically working on them is the way to Overcome Social Anxiety for good!
Following is a list of the ways to get help,
A therapist, i.e face to face sessions.
A support Group, Such as they have at the SAI
Medication but with extreme caution and only as a careful supplement to therapy
Among all these self help is the key to osa, 90% of people fail to osa because for some reasons or others they are unable to motivate themselves in face of the horrible setbacks, and yes there will be horrible and gruesome setbacks, specially in the beginning.
Best of Luck with Everything!