My writing has become tighter over time. Going through the process of writing a book allows for growth to occur. In my second book, Rumspringa, the writing is more robust, and, in the third (Reparation, in progress), moreso. That's one of the enjoyable aspects of writing novels!
When I sit down to write, I must either do something with my work in progress, or accomplish something in support of my writing. The latter could be working on my website, checking on my Amazon files, learning something about marketing, etc. If I find myself totally stifled, it's usually a signal to engage in something active--going for a walk, playing with my basset hound, clearing my writing space, or even grabbing a vacuum and do some cleaning. (I've found that vacuuming can be a valuable time to practice mindfulness). Staring at a blank page isn't helpful!