Book covers are the first things that can be seen and can attract people to look at a book. The design of a book cover must be attractive enough to catch the attention of people and have an appropriate design for the material that the book is about. But it should also not be too expensive that even a stretchable budget won't be able to cover the cost.
There are various types of book covers. There are covers for paperback books and covers for hardbound books. There are also slipcovers made of plastic or fabric for hardbound books and a secondary cover page for some paperbacks. Book covers are created based on a series of design rules, although the rules are not really that different from design rules in general. There are just some particularities that would all depend on the book that is to be designed.
Designers of book covers usually have formal (or informal) design training to bank on. Designing book covers will require knowledge of symmetry, colors, and shapes, together with computer programs like Photoshop and InDesign. You have to be exposed to these and have a certain affinity and facility with using these tools to be able to become a designer of book covers. Of course pencil and paper sketches are still used by designers, but when it is time to present the design, doing ‘magical' design on the computer is a must.
Another aspect that you need to work on to become a designer of book covers is to become a wide reader. Of course you need to immerse yourself in books related to design and art. But if you want to design book covers, be knowledgeable enough about the book topic to propose a design for its cover. Book cover creators should be able to give readers an idea of what that book is about.
Collaboration is also another aspect that makes good book covers. Although designers of book covers generally prefer to work alone, not all of their ideas are accepted on the first draft. A good percentage of the work is rejected either because of legibility or marketability, not because of artistic merit. Success in book fairs is largely dependent on a good book cover, so marketability and legibility are really important.
To make it all easier, there are lots of websites that offer their services to design your book cover. Some have general templates, which you can manipulate enough to get the particular design you are imagining. Of course, there are also websites that offer their services and have designers who have had years of experience designing book covers. These websites may help get your book to be noticed from among the hundreds of books displayed on a store's book shelves.
The future of books on book stalls may be somewhat uncertain because of iPods, Kindle and the short attention spans of children in school nowadays, but there is still hope. Books are great in that they are cheap and portable, and don't need any batteries. So yes, maybe the world does need good designers of book covers now and in the future.