But, these problems, like most others can be overcome, or at least minimized. We all just need to take a deep breath and think about this, then plan a course of action.
Now it's very unlikely that someone is going to yell at you or call you bad names simply because you make a professional business contact. They may not be interested, but really, is that so bad? Move on.
Don't let yourself think only the extrovert and boisterous have a shot at real success in the book writing biz. Here's the thing, nobody knows what goes on inside someone else, but the extrovert is likely to be even more insecure in his or her own skin than the introvert who may not be great out in the big world, but is likely to pretty comfortable with him or her self.
But, to an introvert who's happy and content tucked away behind the keyboard, creating stories, polishing and pampering them, it can be nothing but burning agony to do a cold-call, a sales pitch or speak to a group. It can mean sleepless nights, the jitters and sweaty palms at the minimum.
At the risk of repeating myself, take another deep breath. You, the shy writer, can do this. You can face humanity, you really can deal, make a difference and do it all on yoru own terms.
Practice. Find a conference or workshop for writers nearby or far afield. Attend. Now, it doesn't mean you suddenly have to emerge from your shell and bounce from one thing/person to another. Instead, check out the event before you go. Know a lot about it and decide what this conference can do to help you with your goals. Then grab yourself (figuratively) by the shirt collar and go meet a presenter. Or if not up to that yet, ask a question after a presentation. If you ask a question of someone else it shifts the attention away from you, the asker, onto the person who answers. This helps you in several ways. Hopefully you've asked a question you'd really like an answer to thus getting you some information. It forces you to open your mouth in public in a small way, but experience is experience. You gain just that much more self-confidence.
Make sure you have some nice business cards along on your conference trip and don't forget a professional looking and sharp name tag. Many times the name tag alone will draw people to say hello to you who might not otherwise do so. And if you have a business card to present, all the better. Make a point of keeping those cards handy and presenting them to folks who have something in common with you. Other writers in your field, maybe agents or editors.
While at the conference be sure to observe people, to study how they make introductions or share a story. It will relax you by giving you somewhere to focus and it will provide helpful tips for you to use in your own social interactions.
And, when you meet someone you can use the same tactic as you did in the presentation. Ask a question. It breaks the ice and the added bonus is, psychologically, when you avoid attention to yourself by turning it onto someone else in the form of a question, the other person generally believes you are a very cool and interesting person to get to know. That starts more interaction which may result in the first person introducing you to others (keep those business cards handy). Not bad! The more you do this, the easier it will become. Believe me, I've been there. From close-mouthed, terror-stricken youth to self-confident social networker, that's me! (with shy person still very much present inside) You can do this, and on your own terms. Breathe, take stock of who you are and plunge in.
Oh, and one last tip when you attend a writer's gathering. People do judge you by your appearance even if they aren't aware of it themselves and certainly wouldn't admit it. The fact is, decisions can be influence dby your appearance, what clothes you're wearing, how you look, how your put yourself forward, so keep it in mind, and work with it. Look your best.
That doesn't mean you have to wear a suit or fancy dress. Instead be neat, clean and well-groomed. Wear clothes that are appropriate. That means avoid torn, stained clothes, shorts, T-shirts and the like. Wear something like business casual; clothing that shows respect. It's still generally true that it's better to overdress a bit than the opposite. What could be wrong with looking your best and frankly, smelling your best? Remember, at a conference you'll no doubt find yourself in close physical proximity with lots of other people. Comb your hair, take a shower, use a deodorant, brush your teeth. You want them to remember you for your pleasant company and your good ideas not your ragged jeans, your overpowering breath or that awful smell! Don't laugh, I've experience just exactly that from a few choice others at a convention.
So get out there, you can do it. You don't have to be a star, you just have to be you.