I was an atheist once, but I found that it didn't solve fundamental questions about life and existence. Religion tries to do that but just ends up being man-made fairy tales used to control the masses to follow rules that follow some kind of morals but just end up not making any sense. Eastern philosophy and philosophy as a whole is the next most logical step to take.
I highly recommend reading/listening to Alan Watts (you can find lectures and transcripts online for free). There are other schools of thought, but his teachings and understandings are pretty straight forward and easy to digest (keep in mind some of it is a bit dated, he passed in 1973).
Also, the Tao Te Ching by Lao Tzu. Written for an emperor on how to rule and govern, the wisdom in it is very profound and can set you on the path to living a much more fulfilling life. For the most part, I now follow the Tao not as a religion but the natural flow of the universe, to a point I feel constantly in a state of "wu wei" (effortless action) which makes life so simple it feels like cheating.
Books I keep nearby:
- Tao Te Ching by Lao Tzu
- The Book: On the Taboo Against Knowing Who You Are by Alan Watts
- The Wisdom of Insecurity by Alan Watts
- The Book of Five Rings by Musashi Miyamoto
- The Undiscovered Self by Carl Jung