You’d be surprised at how not having a cover can hold up your book. After you’ve done all that work of research, writing, editing, and revising, if you want to do Indie publishing, you must have a cover. If you are publishing traditionally, your publisher will see to that. But if you’re not, you have to get it done.
And don’t think you can do it yourself – unless you’ve had practice in another life. You might have some requisite skills – graphic arts, design, font knowledge, artistic ability – but even then, they may not be enough to get the look you need for today’s market. There’s help out there. Some, not too expensive. Avail yourself of it.
The illustration you see below is a first draft an artist, Anna Coleman, did on the basis of my description of the cover I wanted for the first Verdura book, A Light through the Cave. We went back and forth lots of times until finally coming up with the cover you see below that. And it was good enough for my publisher to accept. You might want to decide in advance whether you should try this at home.