I saw this on YouTube – https://www.youtube.com/watch?v=4VkgevklB0g
Direct link: How to Promote Your Book with 5 Free eBook Amazon Promotions https://www.youtube.com/watch?v=4VkgevklB0g (around 5:28 minutes long)
In addition, I believe growing an audience on social media, including a blog or vlog, can help before you decide to publish. Some people prefer Facebook, Twitter, Instagram, Pinterest, or a combination of the above. There are advantages and disadvantages to each social media site. Find out where your potential readers prefer.