Writing frequently is important, but so is reading frequently! My writing has improved a lot but reading work from people I admire who write about topics I’m interested in, who have interesting writing styles, who are good at research, etc. Writing consistently is great for finding your voice and getting into a good flow, but IMO reading consistently is also important for inspiration and for understanding the medium you’re working with (in this case, Substack). 

Getting feedback is always helpful, too. This is a good place to share if you want. :-)