Determining reflection points

There's an Acoustic forum over at Audiocircle as I know you frequent there. There's several manufacturers that are very kind and helpful even if you don't buy their products.

Don't forget bass traps. Doing your room acoustics will create a major upgrade that most of us hadn't anticipated and wouldn't do without again.

Just don't over-treat your room.
It's a common mistake.
Start small with 1st reflection points,
then experiment with absorptive/diffusive or both kinds of materials to treat front wall.
Bass traps help with coloration of lover frequencies and will smooth-out a boomy bass in problematic rooms ( I use Echobusters phase 4 for their flexibility. One side is a diffuser and the other is absorber).
In my opinion this would be a good start.
Later you can try treating a back wall.
In my newly constructed room I have used a 1/4inch natural cork tiles to cover entire back wall & few shelves with books as a natural diffusers.
Treating a ceiling is another matter, but not many are willing to go the extra mile.
Email me if you have any specific questions.
I will try to help you if I can.
Good luck & happy listening.

I don't really have any corners to speak of, and since my room is large enough I've been told off-line by a knowledgable person that I don't have typical small-room bass issues, but I do have an 8' free standing wall about 3' behind my head I think I will address.
To this point, thank you all for your assistance. It really helps to hear from folks who've lived through these experiences.