Even if you are ambitious about your newsletter, not every issue you send has to be the best you’ve ever written. Sometimes good enough is just that.
Write a newsletter that provides value to you even if nobody was reading it. It’s a powerful means for building habits.
Be aware, though, that going paid radically changes your relationship with your audience and your newsletter. The newsletter becomes an actual product, your readers become customers. As for yourself, you’re no longer simply a writer, but have to market and sell your newsletter, too.