If I had to start over, I would have built my email list of raving fans first. I was already published on Amazon, B&N, Kobo, and iBooks, but I gained traction by having a readership of peeps on my mailing list who I could contact every time I had a book ready for release.
Something I've learned over time is that the most important thing to focus on in your author business is:
1.) Creating high quality books
2.) Building an email list of fans who want your high quality books.
That's it! That's how you get traction on any platform.
1.) Facebook Ads are still the number one way to reach out to "hyper targeted" cold prospects and get them on your
2.) mailing list. Because Email marketing is the number one way to "market" ..period.
3.) Influencer marketing, or better said outreach, is the fastest way to the top, but not possible for beginners. So I would concentrate on developing relationships with influencers for later launches of your better more polished books.
Having a list to contact when your books are coming out or to take pre-sell orders from is great and recommended; to build you list I have used blogging. This way I can solicit comments about characters, plot twists or even engage in conversations with a growing list while building my list of fans to sell to.