Book fashions are as changeable and fickle as some New York Fashion Week dresses. What looks cutting edge and trendy one year is dated and old-fashioned the next. Even tried-and-true basics can become cliche if enough authors use them for their book covers and descriptions. If your back catalog is more than a couple of years old, you've probably got a branding problem. Most writers don't really think about branding for their first few books, and end up with a mish-mash of covers and titles that don't go together. One look at the big guns in the writing world like John Sandford, Stephen King, or Diana Gabaldon will show you two things: they're not afraid to rebrand their entire line, and they know the strength of making their books look like a cohesive set. Enhance your own book marketing performance by striving to do the same with your work.
You may be in love with your book titles, but it's worth pondering if you might be better off with a cohesive set of works. If your books are in a series or set in the same environment, title branding is a natural. Even if they're all miles apart you can benefit from keeping them in a similar vein. No one says you have to go with Grafton's A is for... approach, but keeping a theme going is a great way to help readers identify your next work.
Covers are the most trendy part of any book offering today. One year it's all about stark covers with lines of bold type, and the next year readers want to see one large picture of an individual item that represents the entire story. There are trends in book covers, and savvy writers latch onto new trends and follow along for added sales. The least you can do is to make all of your books look similar by using the same elements in each one. Find a font for your title and another one for your name, and use it on every one of your covers. Decide on a basic design and never stray from that template. You may have a different street scene on every cover, but if all your covers feature a street scene they'll look like they all belong in a set. Choose a common template for all your work and redo your covers to match this theme.
These book descriptions, found on the back of books or on the online sales page, are among the most important sales tools you have. Read dozens of book blurbs from books in your genre. Most of them will start running together with only a few standouts. Don't follow your gut here. Following the standouts is a great way to guarantee your book will sit and languish without big sales. You want to be part of the pack. Readers see familiar blurb styles as comforting; a style they already know signals to them that this is a book they would like to read. Create a blurb template and rewrite all of your books to follow your new style.
Keep the Faith and May the Force be with You!