I went from being an introvert with anxiety so bad I cried in front of everyone when giving an assigned speech to speech class, to an A-type with endless external confidence, marketable public speaking skills, no shame, and almost no inhibition. This change occurred sometime towards the end of highschool (with a fresh dose of "know-it-all-asshole") and matured throughout college. I regularly try to figure out just what the fuck happened. Who is responsible for this shift? I want to condense it so that others like me can change if they want to. Best I can do is point out a couple memories that I think were "turning point."
1. In middle school I was called "gay" all the time because I was quiet. Back then this was an unacceptable insult and socially ruinous for a 13 year old. I somehow made great friends with a guy who once said "Are you actually gay?" I said "no." He said "who fucking cares anyway?"
2. Freshman year I gave a speech and cried at the beginning from nervousness, the teacher quietly put his hand on my shoulder and made me finish the speech, quietly giving me encouragement, telling me I was doing a great job.
3. Sophomore year I was at my friends' place for an all-night LAN WoW binger. His bathroom's lock was broken downstairs so I'd been using the upstairs one. His older brother (A-type sure-of-himself guy that I admire to this day) went to use the bathroom, announcing he "had to take a dump." I said "oh, use the upstairs one, this one's lock is broken." He said "so?" I asked, "what if someone walks in on you?" He said "I'd say, 'get out of here, I'm taking a dump!'"
4. In highschool we read a book about a little girl that died and was allowed by... god or something... to view certain portions of her life again. She noticed that she wasn't "awake" in any of those memories - nobody was expressing their love for eachother, or appreciation of the moment, everyone was "sleepwalking." I'm sorry, I don't remember the title.
So to sum up my absurdly long post, I would say the things that helped me fill in the social gaps are having supportive people in my life that help me put things in perspective, and a very early introduction to the concept of "mindfulness," though I didn't call it by that name back then. Also, an early introduction to my mortality.
So I guess, support your friends, invite them out even if they don't come (they might eventually), and when they do come out, iron out their faults (I would lash out and be an asshole, and my friends would be so so patient with that, showing me "they right way." Think classic neckbeard arrogant ass.)
But that came with a total addiction to World of Warcraft, Battlefield, and pirated anime, along with all the broken social interactivity that comes with a pale-skinned weaboo spending his summer vacations hiding in his room and worsening his nearsightedness.
I love my parents and because I don't have kids I won't claim to know the best way to raise them, but I will say I wish my dad had learned enough about computers to actually managed to restrict internet time rather that just throwing on a shitty parenting software his coworker gave him that I surpassed in about five minutes. Or, somehow rewarding me for exploring the pirated copy of 3D Studio Max and fostering creativity there. Or, just taking the damn computer away and forcing me to go hang out with people. I was a shitty kid and I know I was hard to manage, but I think that dealing with that is part of being a parent.
I have no idea if I would have turned out struggling less with the things I struggle with now if they had done things like that, but I suspect this is the case. So, you know, don't take my words at face value, just consider it as one perspective from someone who is now an adult and did grow up with nearly unlimited screen time. I managed to fill the social gaps somehow, get a job etc, not all of my old WoW buddies ever managed to.