One of the things about writing is that if you want to improve at all, you're going to need other people to read your stuff and give you feedback. This is true for anything, really.
It's hard to show your work to others. Writing is so personal that if you feel you've bared your soul on the page, it can be scary to show that to other people. You feel exposed, naked and alone.
But it's one of the most important things you can do in order to improve your craft.
If you've written a story, doesn't matter if it's a short story, novelette, novella or novel, you're going to be really into it. Eyeballs deep, in fact. It's exceptionally difficult to get a 10,000-foot view on a piece you've been working on for months or years. Simple errors and inconsistencies will be invisible to you simply because you're so used to your story. You know everything in it and everything that happens. But that doesn't necessarily mean you've written it down clearly.
For example, I once had a short story critiqued in a writing class I took, and one of the main criticisms I received was that the readers found it annoying that they never found out what happened at High Park. In the story, I refer to a past event at a location called High Park. In the first drafts, I never explained what actually happened there. I thought the mystery would be alluring. Boy, was I wrong. The class unanimously felt that I ought to include a description of what happened there. They said I had built up the story really well and the suspense was working for them, but then they got no pay off in the end. They had kept turning the page, hoping they would eventually found out, but then never did. It was a huge letdown. I heeded their advice and added an account of the events at High Park to the story, and I know The Spaceship is better for it.
So how do you get over your fear of exposing your writing to others?
Well, it's hard. It's normal to feel scared that whoever reading your work won't like it. We're only human after all. We all want to feel acknowledged, valued and loved.
My suggestion is to start small. With my novel, I had just two beta readers at first. I'm about to finish a draft in which I've incorporated the feedback of those two people, so I'll look for one or two more beta readers for another round. You don't have to show your work to so many people if you don't want to. Start with one person if that's what you're comfortable with. The internet is ripe with questions you can give your beta readers afterwards that will help them give you constructive feedback and think about your work a bit more in depth.
Just ask nicely and don't get offended if the person says no. And if they are so kind as to read your story, make sure to get them a little thank you gift afterwards.
But a word to the wise: don't be that person who can't take feedback.
If you're going to ask someone to go out of their way to read what you've written, make sure to respect what they have to say. Don't shrug aside all of their suggestions because you think they just didn't "get" your story, or they're not a writer so they couldn't possibly know what they're talking about. If you put your work out there and want to improve, then your readers have the right to their opinion. If you don't want feedback, then don't show your work to anyone.
But like I said, getting feedback is key to improving your writing.
I know it's hard not to take negative feedback personally. But if you go into this with a spirit of learning and wanting to get better, then it will be easier to take the feedback for what it is: criticism of your current ability/work. Not of who you are as a person. Not of your ability forever. But simply of this work right now. Nobody is perfect at everything. We all have to learn and practice. Keep in mind that you want to tell the best story possible. You don't want to put something out there that's not as great as it could be because you got in your own way. Remembering to put the story first always helps me deal with criticism. Maybe it will help you too.
So those are my thoughts about that!
As always, keep writing! That's the other major way you'll be able to improve.