For non-religious, more "empty mind" meditation, you can also look at Zen Buddhism if you haven't already. Zen meditation techniques usually involve focusing on breath or using simple visualizations.
I recommend the book, "Zen mind, beginner's mind" for an introduction to non-religious meditation, written for a western audience.
FWIW, my personal opinion is that meditation is a type of mental training. The specific techniques you should use depends on what you want to train. "Empty mind" meditation is good for training "mental silence", impulse control, and focus. Love meditation trains love, including loving humanity and loving yourself, and shouldn't be underrated. If you have specific goals for self-change, IMO you should use that to create your own "training program" by altering the visualizations used when meditating.
I recommend the book, "Zen mind, beginner's mind" for an introduction to non-religious meditation, written for a western audience.
FWIW, my personal opinion is that meditation is a type of mental training. The specific techniques you should use depends on what you want to train. "Empty mind" meditation is good for training "mental silence", impulse control, and focus. Love meditation trains love, including loving humanity and loving yourself, and shouldn't be underrated. If you have specific goals for self-change, IMO you should use that to create your own "training program" by altering the visualizations used when meditating.