I have an even better golden rule: to become a better writer, actually write as much as you can.

A real example.

I read A TON, since I was a kid (I'm close to 50 years old now). I used to write a lot. I even wrote two semi-decent novels, among other things.

I haven't written much in the last 10-12 years.

Now I want to start a little side project, in which I will write a letter to about one hundred people, print it and ship it physically. I have attempted to write the first one a few times, and it's very difficult. I am not used to write anymore.

Write more.