I know you are an excited Redditor who just can't wait to shout out to the depths of the internet that your book is available for consumption, but hold up for just one minute. Your first inclination will probably be to promote yourself on Reddit. It makes sense: you are an avid Redditor, fellow Redditors should appreciate your work for that fact alone, so why not?
Well, it doesn't really work like that and here is why: First of all, Reddit is a quirky community of hipster-hating-hipsters that are so self absorbed in their parents' basements that they will take any excuse to downvote you. So, when they see some post about another Redditor who has self-published a book, they just roll their eyes and immediately click the upside-down arrow in hopes that all your beloved dreams will be crushed just like theirs.
Let's say, for instance, you have finished a book called, I don't know, Supremacy: Reformation. Let's even say that you intend to tell the story in episodic bites that only take an hour to read, giving those with the busiest of schedules an opportunity to participate in an epic science fiction story. Well, Reddit won't care, even though they could be reading the first episode while they ride the tram or other strange, non-US types of transportation.
They won't even care that they will be directly helping the plight of a 99%er since they will be giving their entertainment dollars directly to you instead of some jerk, 1%er publisher. No, all they will do is make some comment about, "here we go again..." or "400th repost this week...". So, the first thing not to do is make a post on Reddit.
Another great temptation will be to submit one of your own blog entries about your book to Reddit. This is another classic recipe for disaster for nearly the same reasons I stated above. No one here cares about your blogspam and submitting your own blog entries seems kind of desperate, anyway. So, don't do it!
Actually, I don't think there is anyway that Reddit could be used to promote your book. Maybe you could set up your post as an Imgur link, because everyone blindly clicks on those. Other than that, though, nothing will even remotely work. You will be permanently relegated to the bottom of the Reddit barrel.
TL;DR Don't make posts like this one to promote your book unless it's on imgur.