Warning: any one of these links will take between 15-50 hours to work your way through.
"The net is vast and infinite", but search engines can't give the answers you seek when you don't know how to frame the question. Experts speak specialized languages, and they are opaque to the laymen. Also, when just starting in a new field, it is hard to tell the virtues of those who are experts from the vices of those who hold themselves out as experts.
So, here are some in-depth, actual experts, sharing their knowledge. Each one must be taken for where they started, where they ended, and the audience they were and are speaking to.
1. Write About Dragons.
Write About Dragons is a master class on writing, given by Brandon Sanderson. Who is Brandon Sanderson? (okay, those of you who read epic fantasy are staring in amazement at the question; the rest of you are still looking inquisitive.) He's one of the biggest names in fantasy right now, both from his own works and from being the writer who successfully finished Robert Jordan's Wheel Of Time series.
In one of those strange and rare moments of clear-headed thinking by an administrator, he has been hired by Brigham Young University to teach a master class on writing. And for two years, students have filmed the class and put it up on youtube for the rest of us to see. The link above is to a student page that lays out the syllabus, and breaks out the entire semester's worth of videos into topics discussed in each.
Caveat: While Brandon is one of those relatively rare people who can teach what he does well, he is at the top of his game in trad pub. Don't go into this class looking specifically for indie publishing advice; he won't BS on what he doesn't know. Also, it's aimed at pre-published writers. It will include the most basic points as well as the highly advanced ones.
2. Kristine Kathyrn Rusch, "The Business Rusch" and other articles
Kris Rusch, and her husband Dean Wesley Smith, have been in publishing from all sides. They're career writers, ranging across many genres and pen names, decades of work from media tie-in fiction to their own original stuff, short stories to novels. Kris was an award-winning editor, and together they once ran a publishing company. So they have a perspective that is nearly unique, and she spent five years writing articles once a week to explain the publishing industry from the inside, the business end of being a successful career author, working with editors, the challenges of discoverability, and even, after the death of a friend, the very-rarely-mentioned topic of how to do estate planning for your intellectual property.
Check out the "business resources" and the "for writers" tabs at the top of her blog - if you're a writer just starting, the "for writers" contains The Freelancer's Survival Guide, which is a great guide to looking at this business not from a "I wrote a book! Yay!" but a "taxes, business plan, reserves in the bank before you quit your day job" sort of way.
Caveat: Kris started writing these before the indie market really exploded. She starts from a fairly trad-pub mindset, aiming only at getting writers to be able to build a career in trad pub. It's fascinating to watch her change as the market shifted radically, but don't swallow all of her advice without chewing on it and thinking about when she was writing, and what's happened since.
3. Writing Excuses
This is a podcast started by Brandon Sanderson (whose cred is already established above), Howard Tayler (of Schlock Mercenary, one of the few web cartoonists to make a full-time, family-suporting living), and Dan Wells (a midlist horror writer, and good guy.)
Their tag line is "fifteen minutes long, because you're in a hurry, and we're not that smart." For the first 5 seasons, it worked great, because they tackled one writing topic, and each person had five minutes to work on it. In the sixth season they added a fourth person, Mary Robinette Kowal (midlist regency romance dressed up as fantasy), but didn't make the podcast any longer - and that's about the time I didn't find they were going in-depth enough anymore to really be interesting. Which is a shame, because when they had her on as a guest, she had some really interesting things to say from a puppeteering background about character focus and directing the audience attention.
Give the archives a try, knowing that the first season of any podcast is rough. Maybe you'll get more out of Season Six on than I do, maybe not - but there is good information in the first five, and plenty of fun.
4. Dean Wesley Smith, "Killing the Sacred Cows of Publishing" and other articles
Dean is Kris Rusch's husband. He has a lot of interesting things to say in his own right, in a more abrasive style than she does. Every year, he also updates and rewrites a series (and then publishes it when done as a book) called Think Like A Publisher. I recommend that, too.
You'll notice there are workshops advertised on his page. You'll also notice that he doesn't make his living from those; he makes his living from royalties, and WMG publishing, which he and Kris started to put up their extensive backlist... and then inevitably branched out, because they can't do just one project at a time. I've heard nothing but good about said workshops, but have not taken one myself, and can honestly say the advice that is free is plenty good and sound.
5. The Passive Voice
Passive Voice is the instapundit of the writing world, run by "Passive Guy", an IP lawyer whose commentary is brilliant and cutting. The best part are the comments, because that's where you can see working writers chatting about the industry and various events, and actually get a finger on the pulse of the publishing world (indie, hybrid, and trad-only).
Be warned: after reading six months worth of TPV, you'll have learned enough about what it's actually like to deal with tradition publishers in their contract clauses, their attitudes, and their corporate structure that the very idea of an offer from Simon & Schuster or Hachette will set your skin crawling. It's been accused of being an "Amazon cheerleader" site by its detractors.. but really, it's full of authors who have kicked over the can of worms in the bright daylight, are discussing the filthiness displayed there on the ground, and how great it is to have other options!
You'll also regularly see some of the luminaries of the indie world regularly pop up in comments.
Caveat: The unofficial etiquette rules before you start - promoting your own work is verboten, as is discussing religion or politics. The crowd ranges from the hard left to the hard right, from military scifi to erotica authors, so everybody has a little tactful dance they do to avoid pissing in the pool and ruining the unique culture there.
6. And one short site, that'll only take a few hours. Author Earnings
Author Earnings is the ONLY site to try to answer two questions: What does the entire industry, trad and indie, look like in terms of units sales, dollar amounts, and total volume? How much are the authors earning?
The studies you see in the news are, without fail, commissioned by the trad pub, for the trad pub, and completely fail to capture the indie market. Well, that's like saying we're going to study the pizza market - but only look at sit-down restaurants, and completely ignore any pizza delivery information.
So Hugh Howey and an unnamed gentleman (commenters on The Passive Voice referred to him as Data Guy, and he now uses that handle) set out to find a way to capture the data. The first report they ran was met with universal scorn from trad pub, claiming it was incomplete, it had to be utterly wrong, it was only one small snapshot of data and didn't represent the market...
The second report has been met with a deafening silence, because it confirms things nobody in trad pub wants to hear. Such as the "flattening growth and decline of ebook sales"... is only in trad pub, and it's because they're capturing less and less of the growing market. And that there are now more indie authors making a full-time living, than all the traditionally published authors. Go. Read. The hard numbers, and the raw data, about the true market, are right there for you.