I'm not a coach, but I know one strategy that helped me IMMENSELY develop my social skills was moving to a new place where I didn't know anyone (and more importantly, no one knew me) and becoming the social person I wanted to be.
At first I was pretty socially awkward, but over time (1-2 yrs) I became more confident in social environments and my conversation skills improved. I think the "fake it till you make it" worked great for me here.
Obviously there are limitations to this - not sure most people can just move to a new city - but perhaps the principles can be applied ---> put yourself in an environment (like going to a meetup) where no one knows you and act like a socialite