Absolutely the first thing to do is to take some room acoustic measurements and analyze them to determine where your issues are. It is impossible to generically tell you how good or bad your room is without acoustic measurements, especially because your room is not rectangular and is more open plan. Once you have taken acoustic measurements then you are in a position to determine what the root causes of each acoustical issue are. From root cause you can identify the solution and select one that meets your practical, aesthetic and budgetary needs.
For example if you are primarily concerned with the bass then generally the issues are caused by room modes and the 'levers' we have to change that are: speaker position, listener position, acoustic treatment and EQ. Depending on where your bass issues are most moderately priced commercially available bass traps may be wholly ineffective when deployed in small quantities. In you room you may also have speaker boundary interference peaks and dips to worry about.
If you do not have patience to learn how to take and interpret acoustic measurements using REW you might want to use a simpler tool such as XTZ Room Analyzer which gives you usable graphs right out of the gate without need to configure scales, use loopbacks, etc. Particularly in the bass region XTZ is probably the easiest tool there is to work with as the key information - frequency response, time decay and the effect of EQ is all on the same page in the software.
XTZ screenshot:
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