As someone who does a fair amount of writing, I often get questions about my writing process. Writing is an important skill to have in a variety of professional contexts, and while there certainly are differences between writing an email to your boss, writing a blog post, and writing a book, there are also common skills between them that can help level up your written communication across the board.
What are you trying to say?
In most professional contexts, you will be writing because you have something specific that you want to communicate to someone else. Identifying the core of what you're actually trying to get across, and what you're trying to accomplish with your communication, can help you craft your message more effectively.
For me, email is the medium where I have to do the most work identifying what I'm actually trying to get across. Typically, work emails are either sharing information with someone ("here's this new tool I've been working on that I thought you might like using as well" or "hey, check out this weird bug I found") or requesting information from someone ("what are the next steps for me in this project?" or "what is the status of that thing you're working on?").
However, there might be times when it's less clear what you're trying to say. For me, this most often manifests when there's a disagreement of some sort. As an example, I recently got an email from someone about a project he'd worked on that was nearly identical to a project I'd been working on prior, and news of his project came completely out of the blue. My first response was to tell him something ("this was a duplication of the effort of my project", "you should have communicated more with other people before spending so much time on this") but it turned out that what I really wanted was to ask something ("were you aware of the other project at all?", "what are your plans for maintaining and developing your project long-term?", "what potential do you see for collaborating on these projects going forward?"). Disagreements or other emotionally charged situations might lead to you wanting to share information (usually an opinion) but might be times where requesting more information will actually get closer to a resolution.
For blog posts, I keep a running list in Google Keep of potential topics. Sometimes these are fully formed ideas (last month the topic I picked was "my new powerlifting routine"), but other times they are fragments of posts - topics that aren't enough for a blog post in and of themselves, but things that might tie into some other post somehow. This post ended up pulling together 5 or 6 little fragments of ideas that all of a sudden made sense as one cohesive post when my twitter bot had a bad day. Just because an idea isn't worth a full blog post itself doesn't mean that it isn't worth remembering.
I could probably write an entire post on coming up with the details of what Jennifer and I were trying to say in our book, Effective DevOps. (Hell, we could probably write a meta-book on book writing.) It's a long way to go from the general topic (in our case, "devops") to having a book with chapters and sections and sub-sections. We started with high-level brainstorming, some mind maps to start organizing ideas into sections, and then worked on more and more granular outlines as time went on.
Identify your audience
Figuring out what you're trying to say usually goes hand in hand with identifying your audience, that is, figuring out who you are actually trying to communicate with. For email, this is generally pretty straightforward since you have to clearly identify the recipients before you can send it, but for things like blog posts and books that don't have a built-in target audience, this requires a bit more thought.
I've found that a feeling of having too much to say but not being sure how it all fits together is often a sign of needing to identify or focus on the audience a bit more. I think of this the same way I approach putting together conference talks (or talk proposals) - by asking, who is going to have the most to learn from this information, and what specifically do I want them to learn? What are they going to gain from this, and how will the information here impact them?
For example, I'm writing this post as a way of organizing my thoughts for a talk I'm going to give at Write/Speak/Code, so I'm focusing on women and non-binary people working in tech, who will probably be interested in writing about either technical topics or cultural topics related to the tech industry. There are certainly many other things people could write about, but if I try to address every single variation or every possible audience in this post, it would go on forever. I generally find that I prefer writing that is more focused on a particular audience. This allows me as a reader to know more quickly if a piece is relevant to me, as well as usually get more value from it if it is - don't try to do too much with one piece of writing!
Figuring out who the audience was helped immensely for the book - Jennifer and I often found that we had more to say than we could possibly fit into one book, so we were regularly asking ourselves, "who is this section supposed to be aimed at?". It's not always easy to cut things out of something you're writing, but maintaining a focus will be more useful for the audience you've identified. If you find that there is something that doesn't fit your current focus but that you really don't want to lose, save it for another piece of writing in the future!
Putting words to paper
For some people, actually putting words onto paper (or into a computer) is the hardest part of writing. For me, it's the easy part - I've been writing in one form or another since I was 7 years old and I can't actually get my brain to quit putting words into sentences that want to be written down. For people who don't have this problem, however, finding their writing "voice" can be a struggle.
Don't worry too much about having a perfectly "professional" tone. For writing blog posts (at least on your own blog or platform), having your own voice, tone, or writing style can be a good thing - this is what your readers will begin to recognize and appreciate. I've found that in most of my email and personal blogging, my written tone tends to pretty closely mimic my speaking tone. This makes it easier for me to write, and I've heard from people who know me in person that it makes it easier to figure out if I'm being sarcastic (I'm usually not these days! I promise!). If you're writing for someone else's platform, you can ask if they have some sort of style guide to help you out. O'Reilly, who do have a particular style they like to follow in their books, have a style guide and incorporated this into the proofreading/editing process as well, which helped Jennifer and I throughout the process.
In general, I've found it easiest to get started writing with a brain dump, where I write an outline (usually a very high-level one to start - for this blog post I started with just the three section headers) and then begin with whatever is easiest to write. Writing things in order is overrated! I've also found that staring at a blank screen or page can be overwhelming, so if I can get anything written quickly, that generally gets things going and can help prevent writer's block as I go. Generally when I start writing I'll have one thought that's more in the front of my mind so I'll write that first.
I'll often jump around and write paragraphs (or just sentences) in different sections as they come to me at first, and then once I've gotten a rough draft like that, I'll go back through the piece as a whole (proofreading things in order is definitely not overrated!) Depending on how much time I have, I'll wait a few hours to a couple days before reading over what I've written again, since taking a break seems to help me catch more issues than trying to do all my editing immediately.
The writing process for an email is generally more straightforward, since emails tend to be shorter (if your email is the length of a blog post, you may want to reconsider that format). Usually a quick once-over is all the proofreading I feel I need before hitting Send, while a blog post I'll usually give 1-3 additional read-throughs over a day or two. The editing and proofreading process for a book is naturally the most arduous, since there is not only more material to cover but also less ability to fix mistakes - I can't go edit the print version of a book the way I can something on my own blog.
There is more to be said about writing than I can fit into just one blog post, but if you start by figuring out what you're trying to communicate, who you're trying to address, and can manage to get some words flowing, you'll be off to a good start. And if you're a non-binary person or woman in NYC, come hear me talk more about writing at Write/Speak/Code on January 25!