As already suggested, watch the YT videos mentioned.
I used a combination of absorption and diffusion, alternating panels, and keeping 1-2 feet between them. I went with only absorption panels on the front wall and diffusion/absorption on the back wall. Alternating diffusion and absorption on the side walls. Bass traps in the upper room corners. None on the ceiling. It’s made a huge difference in my 12’ x 20’ x 8’ room. Used only for home theater. There is much better clarity in movies, better dialogue, much tighter bass and overall a more immersive experience.