There’s a saying that if you want to be a good writer, you should read. Read a lot, in fact. It gives you a feeling for how others write, whether similar or different, and gets you used to what others produce as far as stories go. Your imagination is fine for coming up with a story line, but if you have no clue how to take the next step and type it all up, reading a finished story is an invaluable example.
I would argue that you also have to talk to other writers, too. Or at least visit with them online or read their blogs. There is a lot of useful information out there, and some people are kind enough to do some homework for you and post links and advice on their forums. Some even chat with you. All of this can save you some hard knocks.
My online friend Jana has such a blog and she often takes the time to offer links on her personal blog and put advice and talk about her writing issues in her professional one. She and I write on different subjects (she writes romance and action in a specific genre and I am more general and stick to platonic adventures) but her writing is far more mature in quality (as she has been doing this far longer), and it has been great to see what she goes through to produce her works, both the highs and the lows. It is from her that I gather quite a bit of the information I share here.
No one works well in a vacuum. Encouragement, sharing, compassion, sympathy, and advice are crucial to improving not only your writing, but also your life. Just remember to take the time to thank those who help you on your way, and pay back the kindness by helping others.