Selling e-books on Amazon Kindle Direct Publishing (KDP) can be a great way to earn extra income as a side hustle. With a little bit of effort and some creativity, anyone can become a successful e-book author and start earning money on Amazon. Here are some tips on how to sell e-books on Amazon KDP as a side hustle:

1. Choose a profitable niche: Before you start writing your e-book, it's important to choose a niche that is in demand and has the potential to make money. Some popular niches for e-books include self-help, personal development, fiction, cookbooks, and travel guides. Do some research to find out what kind of e-books are selling well on Amazon, and choose a niche that you are passionate about and that you know a lot about.

2. Write a high-quality e-book: Once you've chosen your niche, it's time to start writing your e-book. Make sure that your e-book is well-written, well-researched, and provides value to your readers. Invest in a good editing software and proofreading service to ensure that your e-book is free of errors.

3. Create a professional cover: A good cover is essential to help your e-book stand out on Amazon. You don't need to be a professional designer to create a great cover, there are many online tools and software to help you design a good cover.

4. Optimize your e-book for Amazon's search engine: To increase your chances of being found by potential customers, you'll need to optimize your e-book for Amazon's search engine. This includes choosing the right keywords, writing a compelling title and description, and including relevant categories and tags.

5. Promote your e-book: Once your e-book is published on Amazon, you'll need to promote it to get it in front of as many people as possible. Use social media, email marketing, and other online platforms to reach potential readers.

6. Keep track of your sales and reviews: Once your e-book is live on Amazon, keep track of your sales and reviews. Use this information to make improvements to your e-book and to refine your marketing strategy.

By following these tips, you can start selling e-books on Amazon KDP as a side hustle and start earning extra income. Remember that success on Amazon takes time and effort, but with persistence and hard work, you can achieve your goals.

Keep in mind that Amazon's guidelines and terms of services are strict and you have to comply with them to avoid your account being suspended. Also, you can use Amazon's KDP Select program that offers promotion options such as free days, countdown deals, and Kindle Unlimited to promote your book.