If I were to sum up marketing, I'd quote one of my clients who described it as a marathon, not a sprint. It's definitely a long-term strategy. Knowing that, my best and what I think most essential advice is set the goal of getting at least thirty reviews right out of the gate (as opposed to selling lots of books), even before your official launch, if you can. Good reviews are the gatekeepers for having your novel qualify for several different contests and other marketing tools, such as BookBub and Fussy Librarian. The way to get reviews is to:
1. Write and send a personalized book review request for each reviewer you approach. You can find them doing Internet searches, Twitter searches, and asking friends who've had their books reviewed for sources.
2. Put a request in your novel asking for reviews from readers. (The big Ask, never discount how powerful it is).
3. Give copies to everyone you meet, who you know enjoys your genre, and ask them to review it (within reason, of course).
4. Create a print version and hold a Goodreads giveaway either before or as soon as you officially launch the novel. And of course, ask your winners for a review.
5. List your novel on NetGalley through an author/organization’s co-op.
For even more tips for indie publishing, I suggest involving yourself with this three Facebook groups.
Here are a couple of blog posts I did about marketing, as well.
Lastly, these are top-notch podcasts to help you get your head wrapped around the many options available to indies.