So, not only was I a born-in JW but my family moved almost every year and I was introverted to start with. Needless to say I was extremely socially awkward when I left about 20 years ago. For me, changing my natural personality was a matter of survival. I got to a point where it was either die or change, so I changed. The important part of that, for this conversation, is that I knew I had to become more extroverted and so I did some things to specifically break out of my shell. Most of what I did was small and might seem inconsequential but it all had an impact in changing my behaviors overall and in making me the person that I am today. People who know me today would never in a million years guess that I was ever introverted. I still feel that way inside, but on the outside I'm a confident outgoing kind of person. I'll share a few of my insights with you. Sometimes the little things help the most.
Physical
Handshakes: Many people shake hands when they first meet. What you look like is their first impression of you but how you shake their hand tells them what you are really like. If your handshake is weak or you use just a few fingers you often come across as creepy or someone to keep a distance from. If you squeeze too hard or shake to much then you are seen as aggressive. If you hold on too long then you are too dependent. So, offer your hand with confidence and hold it between you and the other person. Holding your hand too close to your own body looks like you don't really want to be shaking a person's hand and can give people the impression that you are timid. If someone has a disability in one hand try offering them your other hand (left to left, right to right) so that the handshake isn't so awkward for them or for you. This actually shows that you took the time to think of them and their needs. Take the other person's hand fully in your own, use a firm but not too strong hold, and shake 2-3 times. Then let go. When you have taken the time to learn how to give a good handshake, you will find that others who aren't as good at it really do give you a very strong impression of who they are and how you feel about them.
Hugs: There was a very distinct lack of physical touch in my family, and not just among the JWs. I started watching my family because I was a product of my family and a product of the JW indoctrination. The men in my family would do that manly handshake thing where they shake hands and put the other hand on the other person's arm. I once pointed out at a family reunion that I had never seen my father or uncles hug my grandfather. They hugged each other that day, both to prove me wrong to prove that hugs are fine. And then, they kept hugging each other at other times too. I started asking people if it was okay if I hugged them when we gave our goodbyes. It turns out that most people appreciate being asked because then people who like hugs can say yes, while others who don't like people invading their personal space can say no and offer a hand instead. Once you break that barrier, that iceway, it gets easier. People are friendlier. And according to a TV show with Stephen Fry hugs should be short, no longer than 3 seconds. Any longer is uncomfortable. There are exceptions to the 3 second rule, like when emotions are running high or when the two people hugging are really close. But generally speaking a hug should last only 3 seconds.
Emotional
Confidence: There is nothing sexier than confidence in a person, and nothing that will more quickly destroy a relationship than lack of confidence in a relationship. Your worry will divide your relationship if you let it. but also what you put out there is what you get back. If you put out worry and stress then the other person will react with worry and stress. If you put out your fears then the other person will react with fear. So try putting out a little confidence. Fake it till you make it. Smile. Before you are going to be with your partner take a moment to do the Superhero stance. I know this sounds stupid but it actually works. Stand with feet a hip apart and hands on hips... or stand with feet a hip apart and raise your hands in triumph. Then smile as if you never had a care in the world and you could do anything! You can do this before a job interview also. Studies have proven that you can build your own confidence by standing like you have confidence. It makes you feel like you are confident. Studies have also shown that the act of smiling makes you feel happy, the physicality of smiling actually releases a chemical in your brain that tells you that you are happy. Use this to your advantage.
Fighting the JW mind tricks: The JWs tell us that relationships in the world won't last and we take that fear into our worldly relationships. But you know my grandparents have been married for something like 60 years and they were never JWs. In fact, I never knew any JW marriages that lasted that long. It isn't just the JW teachings that you have to fight against. Every fairy tale and great romance is about finding 'The One'. But you never see what happily ever after actually looks like because it is a fairy tale. It is not a practical view of relationships. You can be happy ever afterwards but you will also have arguments and will have to work at your relationship and decide from time to time if you want to continue the relationship as you both grow and change as individuals. That isn't a one-time process. It is a process that happens over a lifetime, your lifetime. So, instead of feeding into the fear of what-ifs, just take it a day at a time. Take it one relationship problem at a time. Take it one relationship triumph at a time.
Communication & Trust: Beyond the reasoning against what we were taught, everyone has to learn how to have confidence in a relationship. You have to build trust in yourself, in your partner, and in your relationship. Sometimes you talk it out. You let the other person know where you are coming from, what your fears are and then you discuss together how to overcome your fears. Your partner isn't responsible for your fears but it can help to work through them together. This helps you bond as a couple. At some point, say if the relationship doesn't last, then you have to overcome your fears yourself. You can continue to go into relationships knowing that you have this fear and knowing it can destroy those relationships or you can get some help and figure out how to lose your fear. Relationships take work, time, effort, trust, and communication. Even then they don't always last because people change. Everyone, all over the world, struggles to find trust and to learn how to communicate. This is not just a problem because you were a JW, so don't let your fears from having been a JW overshadow the fact that you are a normal person in a normal relationship.
Movies/TV & Books: Movies and books are not often a good representation of the realities of relationships in the real world. Instead they are snapshots and include some really great information for the socially awkward. Dialogue is the most important part of any story and it is the hardest to write. You read a book and watch a movie and think, 'Yeah, but they have all their words scripted for them". Yeah, by some of the best observers of human interaction that there are. You can't write if it isn't out there. There are bad interactions, good interactions, and the best interactions. Ignore the cliches. Ignore the one-liners. Go for the meat of a dialogue. Want to know what to tell your kid about the birds and the bees? Look at all the examples and think about which one would work best for you. Then adapt it to suit who you are. You think he 'just isn't that into you'? Well, that movie wasn't one of my favorites either but there are parts that can be good information. Chick-flicks aren't the greatest point of view. They oversimplify everything and understate a whole lot. They create very stereotypical ideas about men and women, much of which is wrong in the modern world. But there are snippets at every movie (often when the music gets low and impactful while the actors are talking) that they say something important or handle a hard situation in a way that we can either admire or find distasteful. If you want to know how worldly people react, in general, watch TV, watch Movies, read books. It will give you a good general idea. From there, you decide how you want to be.
Practice Makes Perfect: You can do all these neat little tricks but at some point you just have to practice your social skills. So, join a group that meets for real. Go to a meetup just to meet people if your introductions are awkward. Join a group of people that meet about something that you are really interested in if you want to try to make friends or if you need to beef up your interaction skills. Watch people, but don't just watch people. Speak up. Don't worry about making mistakes. Mistakes are the best way to learn and there is a really important part of social skills in learning how to make mistakes. As JWs we had to be perfect all the time. But no one is perfect. Learning to not just learn from your mistakes but to have grace in making mistakes is so important when learning to be socially dexterous.
I hope that helps.
[Edited to rearrange content I had meant to arrange before submitting]