We have heard of the popular statement "Do not to judge a book by its cover". As sincere as this statement sounds, don’t make this a rule of thumb when it comes to designing a book cover. People DO judge books by the covers! A cover reveals ones thoughts and creative edge into the information that lies within the content of the book. A well thought out cover design should have the potential to look good even after decades.
Now, don’t get me wrong. Creative design is like reading a poem; everybody is going to have a different view. Ones creativity should be tested till you have a “Eureka!” moment. Also, be willing to pay the price for exceptional, gifted artists who are great at what the do. If not, you could end up with something like covers below.