POD Basics
Amazon’s KDP is the most common for POD (Print-On-Demand). You can get the books on at no cost, but file preparation is critical and if you are not experienced in doing so can be very frustrating. Ingram/Spark (I/S) also has very specific file preparation requirements and the initial upload of a new book does not cost anything. But revisions to the text and/or cover after 60 days will incur a fee.
The biggest difference between KDP and I/S is that KDP is pretty much Amazon centric. Although they do have a wholesale outlet it is rarely if ever used. Going through I/S will get your book onto Amazon, but it will also be readily available for customer order from pretty much all other on-line and brick-and-mortar outlets. Sometimes it makes sense to have it on both platforms.
Another thing to note is that although your book is on Amazon and/or I/S, so are a few billion others. Things that help the customer discover your book are the right BISAC code (a category code you select from a list offered), good keywords, and a good description. The description is often overlooked, but is very important. When someone is searching for a certain kind of book the search checks for category code and keywords, but also the description gets indexed for certain words or phrases. Subsequently a book search may not grab hold of the category or keywords but instead be found from something specific in the description.
If you are on Amazon via KDP or I/S, they send sales reports at the end of the month. They do not send a daily report or even weekly report. You can login to your account and find a number of reports, one of which shows the sales to date for the current month.
Amazon is very good at paying for the sales. They are 60 days out from the sale date before they send the royalties to you. For a book sold around the first of December you would see the money at the end of February. The amount of money you receive is the selling price, less production cost, minus 60% of the selling price of the book. So for a 200 page novel sold at $15.00 by the time they have kept their 60% (they consider themselves as a wholesaler) and paid for the cost of the book you end with around $4.00 in royalty. But you have not had to do anything to accommodate the sale.