No matter what type of writing, there is no shortcut. The only way is to keep writing. If you can form a habit of writing journals everyday or every other day, it will be great.
If you can’t find teachers or native speakers help correcting your writing, one self-teaching method is to adapt articles in English magazine. Pick a short interesting one, read through it, jot down those key words and idioms, and then try to rewrite the whole thing by paraphrasing/restructuring with your own way. It is like learning how to walk on crutches. As time goes by, you’ll gradually get the hang of writing and ditch the crutches finally. Writing will become a natural thing to you.
Good luck!