You can use various ways. Few of the promotional strategies you can use for your book are -

1. Share the table of content of your book (with a link)
2. Make a funny infographic and promote it among your friends. You can create a giveaway stating if you comment 'give me the book', I'll choose two lucky people from the comment section and they will have the author's copy
3. Take a screenshot of a page and use an interesting hook as copy
4. Send your book to a book blogger and ask them about promoting your book and pay her/him
5. Use beta-testing of your book. Send the pdf to 10, 20, 30 people. And ask them for their testimonials
6. Use these testimonials as promotional posts

Hope these will help 🤓