That's one thing you can do. There's also reading anything you can get your hands on. Read published books, articles, fanfics... For me, a lot of the improvements that I made in my writing came not only from seeing what my favorite published authors did, but also what people talk about when it comes to fanfics. All I did for a few years was read discussions on forums in the fanfiction sections.
Really, yuki, you're doing a good job already when it comes to wanting to improve your writing. You're posting it to the public, willing to listen to advice. So long as you understand that any advice about your story is from people willing to help you, then you'll be fine. If you wanted to, you could post your story on other forums to get a wider variety of feedback.
I'll see if I can review your fic tomorrow.