Once upon a time, before there were close to a billion kindle books and everybody and their sister decided to try to make these algorithms work for them, you may have been able to game the system, but those days are long past. Now the algorithms to promote works are absolutely inscrutable and the only way to possibly get any traction through these monster sites is through expensive ads, and probably not even then. Sorry to disappoint.
More bad news is that everyone now has a blog and a Twitter account too and most authors get lost in the constant stream and buzz that is the world wide web. Unless you already have an online audience, it's tough to get one.
But it's not all doom and gloom. There are still plenty of things you can do to get your book in front of readers:
1. Contact your local library and see if they will host a book signing or other author event.
2. Volunteer to be on writing panels at local conventions (if you're a genre writer) or go to writing conferences and meet other writers and readers there.
3. Meet new people and be social. Inevitably you will get asked about yourself and your interests.
AND MOST IMPORTANTLY!!!
4. Write more!!!
Write short stories and flash fiction and post them online, or see if you can find an anthology to be a part of. Or, here's a novel idea (pun intended), write another book. And then another. And then another. One of the worst things as an author is to have readers love your work, but have nothing else to offer them. Having more than one title also proves to publishers that you're not a one hit wonder.
So my advice, in short, don't worry about marketing your book. A large catalog markets itself.
I Write, I Edit, I Write Again. Witness!
We're Making Better Words, All of Them, Better Words.
I Write to Burn Off the Crazy.
A Good Day Writing is a Day Writing.
It Puts the Words on the Page or it Gets the Hose Again.
Just keep writing...just keep writing...writing, writing, writing!
Writing is Magic.
The First Rule of Write Club is You Talk About Write Club.
If You Aren't Writing, You Aren't a Writer.