Start with high-confidence spiritualism books, then narrow by subgenre or adjacent topics.
The Wisdom of Insecurity
Alan Watts, Deepak Chopra MD
Be Here Now
Ram Dass, Richard Alpert
A Path With Heart
Jack Kornfield
The Wise Heart
Living Buddha, Living Christ
Thich Nhat Hanh, Elaine Pagels
Attaining Your Desires
Geneviève Behrend
Creative Mind
Ernest Shurtleff Holmes