The more you read, the better you’ll write. Read short fiction, long fiction, whatever style and genre you’re going for, and pay attention to the things that make it work for you. Think about character, voice, plot, setting, and so forth, as well as the language. Why did the author phrase it this way instead of another way? What images does the writing create? How does the writer use metaphor to enrich the text? You might even try reading some poetry, to see some more creative ways of stretching language to convey meaning. Pick some writers you like and think about what makes their writing stand out, and see what techniques you can pick up from them.
The actual writing gets easier the more you do it, and the important thing is just to keep at it. You probably won’t be satisfied with the first couple things you write, but if you push through them and start on something new you’ll find it gets easier. Try to finish things instead of giving up halfway. Also, once you’ve got something, try reading it aloud. See if it sounds natural to you, how well it flows, etc., and that might give you some ideas for improving it.
Finally, I recommend joining a writing group of some kind, and getting the input of other writers. There are several people on the forum here who write, and might be willing to give you some pointers if you want to post a snippet or two. But nothing can really substitute for getting the words out.
