Room treatments and acoustics…. How to begin?

I caution about employing typical commercially available bass traps with the expectation that they will help much below 100 Hz. To better mitigate deep bass modes, incorporating multiple subwoofers (at least two and up to four) will do a better job. You could also consider PSI Audio AVAA devices. 

For the higher frequencies, you will want to address first reflections on the ceiling, floor, and side walls. Opinions are mixed about diffusion and absorption but I endorse absorption.

These two approaches will likely give you the best and biggest bang for the buck but further acoustic treatment is likely to clean up the sound even more.  But at least, start here. 

I am going down this route right now. I got some measurements using REW and now it's time to start experimenting with absorption and diffusion panels. @tcutter why do you recommend absorption? Any and all help is appreciated and good luck to the OP.

Kindest Regards,

For those who suggested GIK. 

I had sent photos and room dimensions to GIK.  I will admit I received a massive email back.  Was it a plan?  Not really.  There were a suggestions but I found it more conceptual than here is a photo, buy this and place it next to that.

 Am I thinking of this wrong?  I did exchange a number of clarifying emails, maybe I am missing something (always possible) but I think I would have expected/hoped for something more concete?

Appreciate any comments - I ask this, because like the OP I want to know where to start.  And I did start at GIK, which was your suggestion...thanks!

@whyrichard   I would humbly suggest educating yourself first, and a great place to start is with Dr. Floyd Toole's book - it's essentially a text book about the physics of small room acoustics.  Learn the concepts, understand that not all reflections are equal, understand why symmetry is important and that asymmetrically shaped rooms (like your system photo shows) needs asymmetrical treatment plans.  Learn about early reflections, decay times and frequency response, and learn to take acoustic measurements using OmniMic or REW or others.  Then learn how to interpret the measurements or send them to me to decipher for you.  Or send them to GIK.  There is so much to learn especially if you plan on leveraging your architectural background for room design purposes.  It's a journey so pace yourself . . .

I’m nothing more…..How to find first reflection point.