
2-You don’t know your market. If you write young adult it’s perfectly fine to publish an e-book as most young adults (about 70%) read on kindles, phones, i-pads and similar devices, but if you are writing thrillers most of your audience buys books. Ergo, you won’t sell an e-book
3-You half-ass your cover. Truth is…most people don’t even read the books they buy (I am not talking to you bibliophile soulmates, devourers of the written word). The first reason why you grab a book is the cover, then you read the blurb, then, maybe, you buy the book

5-You think that your book will sell itself. You have to spend hours per day researching, marketing, and networking. If your reaction is “my job is writing” then hire someone to do the marketing for you

What are you contributing? Would you ever buy a book just because and unknown authors floods your feed asking you to?
Nope. You would unfollow or block them.
So what do you do?
4 good marketing strategies
2-Be consistent.
I have no idea why my book sells. Sometimes I have spurts of sales, sometimes I sell zero books in a day. It is tempting to draw a correlation between sales and social media activity or advertising, but the truth is that some people purchase on a whim, some other take months of getting to know you and deciding you are worth spending some dollars on.
3-Make your book outstanding.
Imagine selling your first book (as in, one copy). Imagine the buyer actually starts reading it (not to take for granted) and is caught up in typos, plot holes and drops it at page 10. Oh well, you sold one book.
But now imagine they start reading and cannot put it down, imagine the book is going to touch their soul and leave them breathless asking for more.
So, read it once more, edit it once more, ask feedback to other writers, redesign the cover...till you feel that it’s the best you can be.
4-Entertain!
Face it, as a writer, you are an entertainer. I don't care if people read your book because it speaks to their inner eye or because they love your trashy sex scenes. Either way, if they choose to spend some of their money and free time by reading your pages it's because they think you're either smart or funny or wise or intriguing. Show them you are, give them a taste of what they'll get in your books. Screaming your title WILL NOT DO.
Remember...“The harder I work, the luckier I get.” Samuel Goldwyn
And after all...If you have a book under your belt, aren’t you already successful? You spent time doing what you love and sharing it with the world. Success should be measured with happiness not money!
Just keep writing.
GBA