If you want to improve as much as possible, you also need to study. This means reading good works on writing, getting in situations where you get advice and critiques, and analyzing writing (which is more than just reading).
I wound up in a job where I reviewed and edited other people's writing regularly and this was also immensely helpful. It made me really get analytical about what worked or didn't, and shone a light on some things that could be better in my own work - both from reading writing that was good and helping correct and provide feedback on writing that was bad.
OTOH I really like the Pinker "A Sense of Style", "Dreyer's English", "On Writing Well", "Steering the Craft", and "The Making of a Story". (There are lots of others I like too, but these are top of mind.)