Writing!
There is no other way. Just keep writing with consistency. I started my first blog 4 years back on Blogger and used to write like once a month. And even in that, I was not much consistent.
2 years back I moved to Wordpress and was little more involved but after some time dropped off.
6 months back I started on Medium and thank to the platform and community I started being consistent from 2 articles per week to 4, sometimes 5 I began writing more and publishing more. And now I found Steemit and life can not be better
And also READING more. This is such an important habit but many neglect it. If I do not read much, I am not able to write much. And the more I write more I feel like reading. Both complement each other.
It is not that first creativity will come and then you will start writing and then you will become a good writer. First, you need to start writing and then creativity will follow and you will become a good writer.