Here are a few books I highly recommend
The Art of Exceptional Living by Jim Rohn. It's an audiobook that I listened to countless time when I started on my personal development journey 3 or 4 years ago. I think it is a very good audiobook for beginners who want to create a more positive mindset. Jim Rohn who died in 2009 was the mentor of Tony Robbins and is still highly respected in the personal development field.
My favorite quote by Jim Rohn: "Learn to work harder on yourself than you do on your job. If you work hard on your job you will make a living, if you work hard on yourself you can make a fortune."
- The Power of Now by Eckhart Tolle. It's a good introduction to spiritual enlightenment. The way the ego works is cleary explained. Ideal for people who aren't familiar with the topic.
- Awareness by Anthony De Mello. In this book Anthony De Mello, with his provocative style, invites us to wake up. Check out his program Rediscovering Life on Youtube. A MUST-SEE video!
One of my favorite quote by Anthony De Mello: "You cannot change by an effort of the will; you cannot change through ideals; you cannot change through building up new habits. Your behavior may change, but you don't. You only change through awareness and understanding."
- I Am That by Sri Nisargadatta Maharaj. It's a classic and a great book on spiritual enlightenment. Highly recommend to people who are familiar with the topic.
One of my favorite quote by Nisargadatta Maharaj: To find truth, you must not cling to your convictions; if you are sure of the immediate, you will never reach the ultimated. Your idea that you were born and that you will die is absurd - both logic and experience contradict it.