To gain writing skills:
Read a lot.
Trust us. Language learning skills overlap each other.
You need to study hard and carefully to improve your writing skills.
Read a lot, write a lot and pay attention to different ways of expressing a purpose or content while reading.
Consider adverbs, adjectives, how to start and end a sentence, paragraph and text, and anything that makes a text eloquent and fluent.
Make notes and use them when writing text.