Read widely, for pleasure first and then with a more critical eye.
In your reading, include plays so as to better understand the importance of (and possibilities available to you) in dialogue.
Join a group, take classes, and/or work on projects where there is great discussion of Story--what is working, what isn't, and most importantly, WHY.
Learn the rules of grammar and punctuation (for your language and country). This doesn't mean that those rules must be adhered to 100% of the time, but if writing (and specifically, writing to be published) is the field you have chosen for yourself, it matters that you understand its traditions.
Be open to critique (also known as criticism). Sometimes those negative voices are right--not necessarily with whatever solutions they might offer, but in the identification of some sort of problem. Writing books, especially, means a lot of words. It's easy for the writer to get lost among them, put the wrong ones down, forget to take the wrong ones out, believe s/he has made something clear that is not yet clear to anyone outside her/his head. Stuff happens. Critics help sort out that stuff.