Thanks JWL for your help.
I updated the sketch in the other post I made (my room has no corners--) you also posted in there.
So right now the thing is a square, and i got your advices
I'll try to make as much as bass trapping on the walls as i can (with air gaps), and then, depending on how it sounds, i will make some stands for the corners.
I'm also considering puting a couple in the ceiling , hanging