Improve your writing by writing a lot

Just like: 

Drawing,

Playing an instrument, 

Singing, 

Running,

Squatting,

Cooking, 

Driving,

Sewing,

Bread-making,

Website-making,

Photoshopping,

Public speaking,

Video editing,

Graphic designing,

It all boils down to the amount of times you’ve practiced. 

What gets practiced gets improved. 

And vice versa.