There is a bit of a learning curve to get a book up on Createspace, but if your book is good, it's worth doing. I get a handy little payment from them every month for my credit repair book, which I published there and also sell from my own domain.
Your title (think headline) and your cover are just as important on Amazon as they are when you're trying to market from your own domain.
* They have a minimum number of pages requirement, which should be no problem for any book.
* They give your book it's own isbn, which is important in the publishing world, and protects copyright.
* It's best to publish in one of the sizes close to 6" x 9"
* You have to allow fairly large margins, especially on the left, because of the binding.
* They have their own cover maker which you should use.
* Do your own graphics and upload to one of their covers. Note: there are options for your own graphics on most of their covers, which are easy to miss.
* You should also have information about yourself for the back cover.
* Price your book competitively with other books in your niche. Here's a strange one: I priced my book at $19.95, which gives me a little less than $10 per book, even though Amazon sells it for $15.56, I still get the same $9.61 per book.
* When your book begins to sell regularly, upgrade to the pro option so you will have wider distribution and get a better percentage.
* You can also put your book on Kindle, which recently upgraded their payment percentage to authors.
NOTE: Unless Amazon has changed things, DO NOT take down your book for editing after it begins to sell. I lost my good position last winter, by doing that. It would be better to give your book a new title and spin the content. Or, better yet, just move on to another book.
Their marketing is great. You do have an idea about how many "buyers" go to Amazon, don't you? Their traffic is enormous.
They give neat previews of the book, including sampling some pages. You can take a look at how they set up my book, "The Black Book of Credit Repair And Dealing With Debt Collectors". Just go to Amazon and search for credit repair under books. My book is on page 2, in position number 18. I used one of their book templates and my own graphics. You can also see random pages in the book.
I hope this helps some of you.