Disclaimer: it really is better to allow for at least some kind of budget to produce and promote your book. A moderate, judiciously invested and wisely exploited sum can pay off very quickly, as seen in the example of fantasy author Alec Hutson (author of The Crimson Queen). If a book is really a good one, a little $$ nudge helps to create a snowball of interest so that very soon, people begin discovering it by word-of-mouth recommendations - the oldest and best kind of promo, but you do have to work a bit first to get there. So those of you who do have some spare money, forego that new bag or your weekly Starbucks latte and invest in your book instead.
Some of us, however, are really in the trenches, financially speaking. We personally are currently experiencing a very, very economically unstable situation, as a family. We make do with old clothes and shoes. We scrimp on food. We think ten times before driving anywhere to save on gas. I'm not saying this to evoke pity or, God forbid, to compel strangers to offer us money, but only for an example's sake. I really, truly have no money to spend on professional book production or promotion. This might change, and I hope it will change, but as of now I'm operating on zero budget. I know I'm not alone, either.
I've heard some naysayers tell me that people who have no money for hiring a professional editor, cover designer, proofreader, Cordon Bleu chef, whatever, have no business indie publishing; that they have to wait until they do have the money, take an extra job walking dogs if need be, etc. But I'm a homeschooling mother of three young kids living in the boonies. We only have one car. None of my neighbors need babysitting or anything. I need to make money from home, and my only feasible way of doing so is by writing and publishing as an indie - with whatever means I have available. Once I do make some money writing, I can take from it and invest it into subsequent books, but not before. So basically, if I wait until I can do this "the proper way", I'm going to wait for a long, long time.
Yet others say, "well, if this is the case, trad publishing is the way for you - the publisher will provide editing, cover design, etc". This is true, and I have experienced the benefits of it while working on my upcoming novel, Wild Children, with Mason Marshall Press. They swooped upon my poor manuscript, mercilessly ripping it apart and punching it into shape. I didn't have to worry about cover design or formatting. But traditional publishing moves at a glacial pace; it takes time to query, get an agent (or even get a publisher, sidestepping the agent), wait while your manuscript is read, edited, formatted, prepared for publication, etc. Your publisher will always have other projects to work on. Nobody is as eager as you are to get that book out into the world. Furthermore, not every book is traditionally publishable. In short, many books wouldn't have seen light at all if not for indie publishing.
So let's assume you're an indie writer on zero budget. How do you go about this, while being committed to giving your readers the best product within your means?
1. Editing: endlessly combing through your manuscript isn't enough. Participate in critique groups, get beta readers and take a good, careful look at any constructive, intelligent advice you receive. Thank people profusely and prepare to beta-read in return.
2. Cover design: this can be a sore point for indie writers without any very impressive artistic skills. I was very lucky to discover Katie Cody, whose covers are not free but very affordable. Katie also has a knack for hitting on the very thing I need in a cover, without me even being aware of it. At worst, take advantage of an online design model such as Canva.com. Just remember, if you are no artist but are forced into designing your own cover, keep it simple. Any excesses will only expose lack of skill. Also, pay attention to image copyright. Free images can be found on Pixabay and other sites. Look for images marked as free for commercial use.
3. Promotion: it's extremely frustrating to think that a comparatively inexpensive ad or professional review could do wonders to boost your book sales, yet you don't have even that sum to spare. There are, however, free promotional venues that are open to you: social media (provided that you alert people to your book tastefully and without spamming), free contests, blog interviews, blog tours, submissions to free review sites. Contact book bloggers (reading their submission requirements carefully first) and, in general, reach out to people. Things will happen slower for your book if you are limited to unpaid promotion, but if you are consistent and, most importantly, if you do have a good book, you'll get there eventually.