From my learning experience, writing skills is harder to learn compare to speaking skills.
Your speaking skill can be improved if you speak English everyday.
For writing skills, different writing skills when it comes to different works.
There is a specific writing skills for exam, business email, casual social media posts, legal document, presentation and etc...
You need different writing skills for different works.
So you have to understand what is your works and what is the writing skills you need for that work. Then only you can improve from there.