I included some pictures I liked in this description. The cover, I think, should include a mix of poker (cards, poker chips, etc.) and psychology (a person, his head, thinking, a picture of a brain maybe).
I like the idea of a design with a two headed poker card, with the up facing head expressing one thing (perhaps intelligence, insight, enlightenment, and the bottom head expressing another (like confusion, doubt, anguish).
Also: The cover should NOT look like an instructional poker book, because this book isn't one. It should stress the psychology (Self-Actualization) aspect, of achieving psychological health and clear/objective thinking. It is a psychology book above all else. (It is a serious book for intellectuals.)
By the way, for those who are not sure: The term "Self-Actualized" approximately means "enlightened." The literal meaning is: "Having achieved the highest level of psychological health."