Take good pictures. Some of the options below don’t require you to actually take the picture and sell the product, but for the ones that do, make sure you take a clear picture that makes your product stand out from the others. If you’re going to be taking a lot of pictures, set up a small “studio-like” area in your home with a backdrop and proper lighting to really make your pictures come across as professional. And of course, you’ll want a good camera too.
You can sell your ebooks through Amazon's Kindle program or Apple's iTunes Connect, which gives you access to a large majority of the digital-book reading market and the barriers for entry are incredibly low. You don't need to invest lots of money to make this happen, but you do need to invest lots of time, not only in writing the ebooks, but in marketing them as well.