My first book took 2 years to write, six months to edit, and was on the shelf at Barnes & Noble and Borders for about two and a half years. At the end of that time, I wrote my second book. That one took me less than half the time and stayed on the shelf for about two years. And I continued to write a new book frequently enough to always occupy just a tad bit of shelf space. An author could write a book every year or two and make a pretty comfortable living. I have always had a full-time job in the Information Technology (IT) industry, but not everyone I know who writes does; many just write about technology and are very happy doing so.
To make things easy, many had an agent who managed their book contracts. These agents knew the publishers, helped to get a concept in front of the publisher, and then managed some of the process. Deadlines were pretty static. After all, the publisher bought massive reams of paper to print thousands of copies of each book, and had grammatical editors, technical editors, and layout editors all lined up for certain dates, based on when an author agreed to provide chapters.
That was before everyone had a blog and a dozen different revenue streams. Fifteen years later, much has changed. You can certainly still make a living writing about computers and IT, but the routes you take to get there are very different. Few have agents. Many authors self-publish. Most authors have websites with constantly updated content (blogs). Many have podcasts and submit video content to various sites. Some are also trainers. IT comprises a small part of the overall publishing industry, but is indicative of what many other areas of publishing sees. The way that technical authors go about publishing is also indicative of how authors of other types of content can make a living at writing as well. TLDR: diversity.
If people aren't just writing books and letting publishers market them, what routes to the writing market are people taking? Let's take a look at some, and how you might find this kind of work:
* Corporate technical writing. This is great for Subject Matter Experts (SMEs). In writing, you can usually make a lot more money if it's anonymous. This can be true for people that ghost write autobiographies, but in the technical world this translates to writing manuals and blog posts for companies. Many companies look to the SMEs in their field to help with technical documentation, but you also see the occasional post on Upwork, which has an entire writing section, or other sites. I've even seen people post on a site like fiverr.com, to either have blog posts written, or to write blog posts.
* Sell advertising on your website. First you need a website, of course. One of the reasons why the book publishing industry has changed so much is that there's so much free content available on the web. If you make a decent amount of content, and get a good amount of traffic, then this can be a great revenue stream. The easiest and quickest way to get started with selling advertising is to get accounts with sites like Google Adsense, Yahoo, Bing Ads, Adroll, and tons of others. Make sure you know what you're getting into though; some sites will put adware in your sidebar, which is likely to alienate your hard earned readers.
* Self-publishing. There are a number of ways to go about self-publishing books. There are sites like Amazon or the iBooks store from Apple. There are also print on demand publishers out there that will let you upload your book and then print the copies required when people purchase books. You don't get the built-in editorial that you get with most curated books that are print on demand, but you can publish quickly and hire that stuff out yourself, when needed. One thing to keep in mind is whether you wish for each of these avenues to get a longer work to market require that work to be exclusive. I like the strategy that Amazon takes: work does not have to be exclusive, but if the work is exclusive then you'll make more by sharing proceeds from other authors.
* Magazine articles. Most magazines that still ship physical copies to subscribers make money based on the subscriber. If a subscription costs $20 per year, that money is highly amplified based on the advertisers that buy space in the magazine. You can make about half as much as many books pay, while only writing around 5 pages of content. Each should have something new and fresh, and keep in mind that once it's printed, you can't go back and edit anything!
* Writing articles for websites. This replaces most magazine publishing efforts. Many websites with niche markets can pay pretty well. Non-niche markets come with a lot of competition, but a talented writer can still get a lot of information published. Most have a Submit button somewhere on a page. Or you can get in touch with an editor. Those can be hard to find, but few will turn down a good article, whether you're part of their team or not.
* Writing books. I decided to keep this in here. Because you can still find a publisher who wants to publish your book. And writing this kind of book is a great exercise in keeping with deadlines, in project management (getting a large body of work out the door isn't the easiest thing you'll ever do in your life), and a great way to get legitimate authority in your field. However, if you look at how much you make per hour of time expended, you'll wonder why I've been crazy enough to write as many books as I have.
* Consulting. I'm what some might call a Subject Matter Expert (SME). This isn't to say that I really feel like an expert, but for over a decade I've written about Apple servers and large scale deployments. This is a pretty niche market. There are a lot of authors out there that write about whatever they can sell a book about. For example, Google Apps one day, Twitter for Dummies the next, and then removing viruses from your Windows 10 computer the next. Works of this type are typically skimming the surface of a topic. And that's great. There's more of a market for that type of work than there is for deep technical information. However, those who are SMEs can make a good amount renting out their technical chops (or management training, or whatever your specialty is) for an hourly, daily, or monthly rate.
* Training. Writing training materials for a company can pay more than almost any of the other items on this list. Writing training materials, and even building video based training for third parties can pay a bit less, but is also still a great way to convert your knowledge of a topic into cash. Training for technology is a skill. Leaving a trainee in a state where your next lesson picks up, making sure they see the exact screen you reference every time for each screen you reference, and of course laying out content that flows properly while having the necessary information is always a challenge. This is why some people have doctorates in training. But, I find that most companies who engage people to write and deliver training often have a system and if you just plug into their system (without bugging them with how their system can be better) that you can get a lot of quality work out there without a ton of experience. You can also monetize videos with YouTube. This is a slow and tedious way for some to make money, but it can happen.
* Conferences. Most conferences aren't going to pay you a dime to come and give a presentation. Or they'll give you a boatload of money if you're famous. Since most readers won't be famous, think of speaking at conferences as a great means of getting your writing brand out there. It's marketing for your writing career. It's also one of the more stressful things many will do. You have to get up in front of a group and say stuff. You may spend hours preparing a presentation and then you should spend hours delivering that presentation in a mirror. It's a lot of work, that you'll do for someone to cover travel expenses at best. But you'll meet a ton of people and you should get new loyal followers each time you do it.
* Kickstarter. If you're a SME, you might have a great idea for some work that should be published. If a publisher can't identify that a market is large enough to publish printed materials for, or if you wish to get a good idea on market sizing yourself, you could start a Kickstarter (or one of their competitor's sites) program around publishing a work. This is pretty low risk. If enough people don't contribute, then you have nothing to do. And if they do contribute, then you have a guaranteed outcome.
Each of these avenues pays differently. Some don't pay. Some, like the more than 3,000 blog posts I've written on my personal site, include a considerable amount of effort for little to no revenue. And that's ok, especially if you're starting out. At first, it's all about exposure. If you're a seasoned author who's been focused on one medium, hopefully this article gives you some ideas for other things to go after. The world is changing, getting more interconnected. There's value in all of our efforts. Picking the ones that you focus on is just a matter of choosing which you value most.