Abdi Aden, author of Shining and Yes I Can is very successful at promoting his books. Here are a few suggestions from him based on his experiences:
My PR is very basic and low budget.
Word of mouth anywhere you can, such as my kids’ basketball, take-away shops, public places.
Schools I visit and speak at.
Making t-shirts.
Websites, also other book-sellers
websites.
Calling places saying “I have a book.” For example, some writers festivals, and also Dymocks Camberwell runs a book night every November for self-publishers.
Social media like Instagram, Facebook, Twitter and LinkedIn.
Also learn when new social media come up like Snapchat.
Find small festivals, such as Clunes — self-publishers do well there. People attend from all over the world,