I like the cover to somewhat match what is going on in the story. Colors need to pop and realistic look to the cover. I believe the cover, along with the synopsis can sell the book.
In my opinion the story needs to flow in order for it to be readable friendly. I start with writing my outline and developing my characters. I write a lot of notes down because I have experienced many flaws when I set my writing aside and come back to it, mistakes get made and a lot of corrections need to be fixed. For example, in the 'Fated Destination', my daughter was proofreading for me and she brought it to my attention that Kally was pregnant for a total of 18 months, hahaha. I had to go back through and fix the mistakes made in the flow of my writing.