We also offer strategies to instructors on how to promote their courses here, and you can always get advice from fellow instructors in the community. Some of them have shared their experiences in this compilation of the best posts about marketing.
I generate 50% of my average monthly Udemy revenue of ~$2000 by sending promotional announcements containing coupon codes to my other courses. Of course, I have 64 courses to which I can send promotional announcements (> 500,000 announcements per month).
Each instructor's marketing strategy plays to their strengths.
