I think the struggle for a lot of adults is not in the interaction or in the start but in the maintaining relationships.
This is easy in school and university because of the free time and co-location, the challenge is to do it when we all go our separate ways.
In that sense I do feel like I lack the skills and the mental CRM system to keep walking those friendship footpaths before all the weeds and time make these footpaths slowly vanish.
So what I'm saying is: not sure it's a skill problem (it might be if we're talking about staying connected to what you need) but a societal problem
That is all. I am no messiah claiming to have a panacea for loneliness, but just a human being offering help to other human beings.
Hopefully I can go further than making people feel good momentarily. I will think and work endlessly for that end.
Again, I know it does not work for everyone, but sometimes throwing yourself in the deep, away from your own comfortable home situation, works wonders.
When I travel solo, I become much more introverted. I think that being in your own head has a stickiness to it, so if you're in it for a while, it's hard to snap out of it. You can also be quite weary after a day on the road.
You might also find solo travel difficult when you're around other people. I love solo travel when I'm in nature, but Friday nights in cities can be dreadful.
Still, you will meet people. You don't have to be extroverted, just open to talk. If you're not curious, other people will be. They'll throw you the ball. You just have to throw it back. Bless these people.
However, the stereotypically cold Germans were actually highly receptive of a random stranger talking with them. I was invited to changed destinations a few times to hang out in random cities, and started a couple friendships.
Of course those were also people taking advantage of the 9 euro ticket, so there's a lot of selection bias here. :)
I also think that if you're avoidance strategy is withdrawing from social life, changing your location and not staying in all day is the key ingredient. You can't get your needs met at home.
This is what helped me, when I was in that position.