Hi, Jackie! This sounds like an interesting and important project. There isn't a hard-and-fast rule about using a black cover for a non-fiction book, including one on women's leadership. It's more about how well the cover design communicates the content and how it "speaks" to your intended readership. Although solid black color is usually more associated with death, darkness, and very bleak politcal issues, perhaps. You may be better going with the blue/green option. Our best advice would be, first to look at the color schemes that the bestselling books most like yours have. While standing out from the crowd can work, also following the core conventions can be a better idea. Make up a list of, say, half a dozen covers you like and then get in touch with a professional cover designer. Otherwise, if you're working on the design yourself, create several versions and ask for feedback among your friends, independent booksellers, and on your social media. These are tough choices and there's no one-size-fits all solution. We hope that helps and if you'd like one of our experts to contact you, let us know and we'll ask one of the team to shoot you an email.