How? By writing on a daily base. It doesn't matter if you are good at it or if you are a native speaker. The great thing about free writing is there's no need to do any investigations about the subject you write about.
You just write!
We can only improve skills by practicing.
So let's do it.
Pick a word and write for ten minutes about this particular word. Write what pops up in your mind. There's no need to compose a great story or poem. What you write doesn't need to make sense either as long as you write and... keep writing. Set a timer and keep typing until your time is up.
You can ask anyone to give you a word, use one out of a news item, or write about what keeps you busy.
You'll see if you continue with it, you learn, grow, and above all notice that writing can be fun too.
My head is always busy, filled with thoughts. I write way more than I speak and never have had a writer's block but... I did join freewriters on several platforms and did learn a lot and still am. It would be great if you join me here. Join the community of free writers.
This photo can be found on pixabay.com