It might be worth looking into whether the books written by Uma Silbey and Diane Stein are a good fit for your store. Those were the authors whose works I read first, when I began learning about crystals, chakras, etc. years ago.
Great suggestion and timely. I have just ordered Uma's Crystal Ball Gazing as I am teaching the use of crystal oracles in Glastonbury next month & am yet to find a decent book I can recommend on scrying with a crystal ball!
For many that are just being reacquainted with their spiritual selves, I liked Shakti Gawain's Creative Visualization. I also enjoy "The Laws of Attraction", and "The Mastery of Love", by Don Miguel Ruiz. Last but not least, "The Alchemist" by Paolo Coehlo is an absolute must read.
Speaking of which, I think I need to spend some time organizing my own shop.