I have answered this at Quora.
I teach a Creative (business) Writing course online, so, when I started, my first step was to build a website and adorn it with all the details with a view to my courses. Nevertheless, I first started writing on my blog in 2014, which prompted me to start teaching about it, along with my other business, finance and legal courses.
But building up a website, optimizing it, networking, writing blog posts every day take a lot of time and tremendous amounts of work, also because search engine optimization is a life style for a website, as one can never say, “I have just finished optimizing your website, my work is done”.
Other tips (borrowed from the great Seth Godin) are concerned with developing your reputation, your Body of work, and your cohort.
I do hope these have been helpful for you, and I wish you an enduring and wonderful career in teaching.
Art - Henrik Nordenberg. Source: Pinterest