I think that social skills really are muscles that need to be developed and maintained. Have you ever tried brushing your teeth with the wrong hand? No amount of thinking and focus will get you the same fluidity as using your usual hand. Instead, you need to just suck for a while and practice until the muscles passively develop. Others have mentioned going to bars or the gym, but I'd also recommend joining a hiking group, a book club, or even attending a church that matches your beliefs. Basically, any sort of activity that has a somewhat consistent group of attendees and where the main focus of the event isn't talking. That way you can still feel successful even if you say very little, which can hopefully reduce the overanalyzing and self doubt that comes from awkwardness.