I recent set up with a new habit - one of those tricky things to set up. I've started journalling. This isn't an every day thing, and there is no way that anyone is gong to be looking back at this and pondering on the genius. Most of it is in point form in my own shorthand, serving as notes for me.
It started as a gratitude journal, a pretty highly recommended thing in some circles. It felt really weird trying to follow that process though, so I started to tweak it and change it into my own process and way of doing things.
After reading about other writers and how they work on their journals, I started to incorporate parts of their processes. Each day that I remember to add to it, I touch on how creative I've been feeling and my own views on my quality of work. I also record when other people say really positive things about my work. On the bad days, it creates a concrete thing I can look back over to remind myself "you're getting better", "you have good days", and more.
This isn't a place where I put story ideas or anything like that - it is just for me working on my internal head-space. This has helped me move myself forward at improving my work.
The biggest game changer I've found is improving my efficiency. Since taking this on, I've been able to come to projects with a head that is clearer and more prepared to work. The bad days are coming less and less often, and they're easy to handle when they do.
I really can't recommend this enough as an option for something to do. It is a great way to get warmed up in the morning for your upcoming writing work. Emotions that you don't want percolating into your real work can get put here instead.
So, that's just been one small thing I've done that has cleaned up my writing just that little bit more. The act of writing isn't one where you find the secret way to do it and suddenly find success beyond your wildest dreams, and instead is a process of incremental improvement over time.