My entire book marketing strategy is basically, to focus on conversion and visibility.
Conversion = how well your cover, blurb and reviews work to convince readers to buy.
Visibility = putting your offer in front of the right readers.
A successful book launch is about more than just hitting #1 - you need to stay visible with little or no promotion long term; I do that by building my own email list of targeted readers with book giveaways, and building content that shows up in search results when those readers are searching for content related to my topic or genre. This is all, basically "premarketing" - so while it's a crucial part of my book launch process, it may not seem sexy if you just want to launch hard with paid adverts (you can do that, if you want, but when your book stops selling, you should come back and repeat this section.)
I lay out my methods pretty well in the above video, and talk about KingSumo, Gleam and Bookfetti for book giveaways (if you're in this course you should have access to the Bookfetti app already - it's in the "1000 Subscribers" course).
I made several other in-depth videos of this process and added them to these blog posts:
How I got 8500 subscribers in 1 week
How to get bestselling authors to promote your book for you
Mainly, I ...
1. Build "best (genre) books for (type of readers" posts with lots of keywords, feature other authors
2. Tell those authors I featured them (to make friends and so they share if they want to),
3. Do a giveaway of those and/or similar books
4. Advertise that giveaway to target readers (people on Facebook who "like" the genre, subject, other books or authors, similar movies or TV shows).
I repeat that process for every book I publish, trying to get lots of backlinks from high authority sites to those pages, so they rank well.
Over time, you'll start getting organic traffic to your site (free visibility!)