I suppose that I'm an author now, and I believe the typically done thing is to give advice on how to write things to those who aspire to get published. As it happens, and as you may already know, I didn't actually intend to become a writer. It just happened one day. I've never looked up ways to overcome writer's block, I never looked up ideas on what to write or put in my book, and everything I produce comes entirely from myself. I doubt this will really help people trying to become authors or who are just trying to get some advice.
Firstly, if you're coming to me for writing advice, then consider me suprised and flattered. In fact, I am both of these things if you only read the book. The whole thing just turned from a few pages and a diagram into a "publishable" work. I am still quite surprised it hasn't been banned or something for so many possible reasons. My intention at the start of this whole project was simply to get down an idea I'd had, to write it and make it more solid in my own mind; perhaps even give it the possibility to be shared with some very close friends. This first idea was in fact the final chapter of the book; I wrote it in a very bizarre order which half made sense at the time.
Since I didn't actually intend to sell a book or even publish anything in the beginning, my ideas have been sincere and worthwhile, at least to me. I never intended for it to just become "another self-help book," and in fact I'm slightly revolted that it can be included within that category. The ideas I put down were just genuine ways in which I managed to help myself live. I don't just cope and put up with things, I actually enjoy certain aspects of my life. It has radically changed me, and that's the truth.
I suppose what I'm saying here is that my best advice is to write what you know. I've not needed any guidance, because I haven't run out of content. I've always had something to say, simply because there's always so much going on. Perhaps it's an easier genre to write than the realm of fantasy, because you can't live fantasy, ipso facto, and you can't know it so closely. If you live and breathe ancient Roman history, and you want to write about it, then you shouldn't have a shortage of ideas, so the second piece of advice would be on how and where to start writing.
Personally, as mentioned, I started at the end. It wasn't an intentional, snobby, pretentious move; I simply wrote that first and thought it was nicer at the end. If you've got something to say and write and convey, then all I can say is start writing it.
It's similar advice I give for everyday life; do it now. If you're wondering when to start your first chapter, just do it. Just get your keyboard out and start slamming on some keys with a vague notion of what you want to say in your head. Perhaps try and keep the tone and language more consistent than I've been, that goes without saying, but my inconsistency was part of my plan, in a way. I doubt it's easy to pull off in other books.
When it comes to continuation, I find that it's perhaps the hardest part of the creative process. Just sticking with something long enough for it to become created. Personally, I've never managed before, but I also never had such great advice before from the most insightful of all sources (myself). As you may already know, I create schedules for my days. I plan every activity that I want to do, the times I estimate it should take me and I even plan in my rest and breaks. I've gotten good at knowing when I'd probably like to eat, take five, etc, and my plans reflect that nicely. When I was in the process of creating H²ELP, I just scheduled in a couple of hours in the day for working on it. Some weeks I'd work every day, other weeks I might only do three days, but it worked. I would start and finish a chapter in one go, usually, as to keep the creative spark of an idea alive. So if you can plan in your writing hours, by all means, do it. Just write something; even a page a day is productive and better than nothing, just keep going and keep persisting.
I also planned in a half hour every morning when I could just have some time to think. No distractions, just a chair, a drink and occasionally a cigarillo. I would imagine scenarios in which I'm hearing people or talking to people, and giving them advice or taking on board what I think they would say. From that practice, I gained enough ideas to complete the entire book, so it must have helped. I believe that we, as a society, don't just spend time doing nothing anymore. That is to say, we LOVE distractions. We're always on our phones or watching TV with every spare minute we have, and I often wonder if that's a reason why I've not had any good ideas in years. Since I started trying to give myself time to think and since I've also cut back on the digital tools I use, and more importantly how I use them, I've managed to accomplish so much. Perhaps that's just myself finally realising how to be productive, or perhaps it's a result of prohibiting less productive activities. It sounds like it's a boring existence, but I assure you, it is highly satisfactory. Besides, generally, if you want to publish a book, you might have to make some time-sacrifices and change some of your habits which aren't conducive to production.
I'm lucky that I'm a rather fast typer, and it didn't take more than two hours to write a chapter. I went through and checked them all afterwards, of course, but most of the content was put down quite rapidly. All in all, it took a surprisingly brief amount of time to complete. I know it's not the longest book in the world, and you can be grateful for that, but too much more - in my opinion - would have served only to dampen the impact I wanted the book to have. I didn't want to dilute my ideas with less worthy ones.
So that would be my final piece of advice: know when to stop. Your ideas probably aren't as good as you think they are, even if you don't think they're very good, so bear that in mind when you start getting bored of reading through your own work.
I believe that just about anyone can write a book. We all have our own lives and ideas; and if all of these celebrities can have autobiographies, I don't see why anyone else can't. Essentially, I'm using the reasoning of "we all have a story to tell," which is true. So go on and do it, you don't really have a good excuse. Steven Hawking wrote several books, and he probably had a harder time than most getting his ideas down, so if you're trying to justify not being able to write, I'd say you're not trying hard enough. We only suffer failure once we've given up trying.