A room of your size will require somewhere between 100 and 140 ft2 of 2" acoustical panels between the 4 walls and ceiling, plus 2-4 Bass traps.
Without knowing more about OP's room -- wall materials, rugs, furniture (especially couches, etc.), windows, etc. I'm not sure where in this estimate his room falls, indeed if it falls within this range at all.
No disagreement that doing the math is important, but the math can only be done if as much as possible about room contents and materials is known, first.