Therapy first of all.

Also having one or two "safe" friends that you can practice being social on, as dumb as it sounds. For me they are my best friends who I experienced little anxiety with to begin with. Talking with them always helped my confidence because it showed me I could hold a conversation and be fun just fine. For a while I was pretty dependent on them in any social situation, I'd feel so lost without them. But they were fine with me "using" them in that way, and one of them used me right back when she was anxious haha. Slowly I started getting to know more people and feeling less anxious every single time. I still get major anxiety with certain people or situations now though, but I've built my inner safe circle up enough to not have to dread hanging out with people everytime. I try not to bail on plans even if I'm nervous, because isolating just feeds the socially anxious monster and I never wanna reach a point of complete social isolation again.

I guess I realized it's okay to need a little extra support or time with things. I started small and slow, and am super proud of what I've achieved. It's hard (continuous) work but definitely possible.