Book covers are the most important marketing aspect of a book. People will make impulse purchases if they like the book cover; the cover is what gets a book attention. Covers that are white backgrounds with large text tend to look amateurish. You also want covers that persuade people to buy the book, with good flap copy. Use the template from Para Publishing to write effective copy.
Para Publishing also has a list of resources for cover design. According to Lynette Phillips, Attention Grabbing eBook Covers Don’t Have To Be Expensive. You can hire college students who are studying graphic design, for example. To get an idea of what goes in to the making of a book cover, check out the YouTube video, Making of an Indie Book Cover.
For examples of cool book covers, take a look at my Book Covers Pinterest board.
UPDATE: You can also send your book covers to @SelfPubBkCovers, who just tweeted “Is your
#indie #selfpub cover as good as a Big 6 cover? Send me the buy link. I’ll RT it if it is, & tell you how to fix it if it’s not.”