What is the best way to approach improving room acoustics?

I fully get I need to minimize the reflections in my video room, but it is a living room. I have many windows, multiple entrances in and out of the room, cathedral ceilings, and even a large window in a wall to view the TV from the Kitchen. 
It is the only room in the house available to do media, so please, no suggestions to just add a $100K addition to the House. 
I’m thinking of hanging heavy drapes over the windows, lots of rugs and need help with what bass traps and acoustic room treatments actually work?

I did get the Marantz 8805 with Audyssey Platinum room correction software for room tuning. It is a 7.2.4 Dolby atmos system with Rotel amps, all Focal Electra speakers and 2 Canton subwoofers.
it has the chance with help from you experts to be a special video room. The TV is the LG OLED65C8PUA.
Thanks for the recommendations.