I’ve done a few presentations on this at FC over the last few years, so there are a few things I would recommend:
The style guide from smashwords. It is well worth reading, especially if you are going to post there. But it’s really good for all ebooks.
The contract you must agree to, to publish on Amazon (as well as the ones for any other services you may publish through), reading and understanding them is actually important and will save you a lot of grief. I’m not putting this up here to be trite either, I’ve seen a lot of people get into a lot of trouble (legal and otherwise) because they did not bother to read the contract. Amazon and the other companies will not hesitate to take action if you break or violate your contract. This includes lawsuits and legal charges.
Kindleboards: http://www.kboards.com/ There is a wealth of information here, as well as a wealth of resources, a number of freelance editors and artists advertise there, plus you can ask other authors questions. Some of the more successful independents post there, people who have sold several -million- copies (sold, not giveaways) and it is always interesting to hear any advice that they may give.
ebooklaunch.com is who I hire to do most of my covers currently, they provide other services as well at a good price, so I figure that I’ll plug them here.
ACX.com - if you want to do audible books on Amazon, these are one of the bigger options (Amazon owns them now). They don’t pay as well as they used to percentage wise, but they’re still pretty good.
Very Important: Amazon categories that you can only get into by using keywords: https://kdp.amazon.com/help?topicId=200652170 A very important webpage. This is for when you choose the two categories and seven keywords when publishing on Amazon.
Also, I don’t have the links, but about once a year Mark Coker of Smashwords does a blog entry about the indy market, talking about such things as price points and sales trends. You should read this every year. There is also some research on price points and such by another group, but I can’t recall who did it. They’re the ones who came up with the 2.99 / 3.99 suggested price points for most indies (Romance usually gets different rules, just fyi)
www.nookpress.com - B&N ebook website. Rumors of their demise are greatly over stated. Romance sells especially well here.
Calibre E-book management - a really great tool for converting ebooks between different formats. Free
There’s more, (there’s always more) I’ve been self-publishing with Amazon, Smashwords, and B&N on the internet since '11. I am always willing to share what I’ve learned, or how I do things, if anyone is interested.