When librarians involved in readers advisory trainings advise library workers to avoid putting bestsellers on a display, there is often a lot of pushback. No one is suggesting that you not buy the most popular authors or those breakout hit titles. What is being suggested is since book displays are a form of marketing for your collection, it makes no sense to waste that space and effort on the titles with long wait lists and a solid fan base. If you have a long list for Rebecca Yarros, you don't need to promote her books. (Other than using them as a source for "read this while you wait for ..." displays.)
Remember that what needs attention at one library will be different at another. There can be genres, authors, and titles that fly off the shelf at one library but languish at another. I can't tell you which titles need attention at your library but whomever runs reports for you can do that. Because it is your collection and your library, you will need to adapt whatever collection marketing ideas to your library.
Rather than worry about creating something super creative with a snappy sign, start with some reports that list titles which haven't circulated in awhile. Look at what new releases haven't found their reader yet. Make a sign that says NEW! or FICTION! or CHECK US OUT! and put up your display. What gets books checked out is the face out and the creation of a smaller collection on the display.l Someone on staff may find a book they love on that display and can hand sell it to a patron who needs a great read. By investing some attention in in those titles, you will have given them another chance before they are deselected.
I also suggest that libraries invest in easels for their shelves. At the end of your shelves, put one title on an easel. Titles faced out like that will get attention and will likely find their reader. It's a low effort way to promote your collection that everyone in your library can fill them in when they pass an empty easel. It's not a huge investment but will have a great payoff as far as getting titles in the hands of readers.
