Ok, first off I recommend you use one of the room size calculators online to get a rough idea what kind of frequency modes you can expect with your room dimensions.
If you suffer from flutter echo (you hear a spring reverby “sproing” in a decay tail if you clap your hands as loud as you can in the room), it is easily eliminated by adding more soft objects into the room. Also a heavy carpet and heavy drapes can tame the higher frequencies too some degree.
Next, you need to write down the most dominant room modes and research for bass trap solutions that offer plenty of absorption in your dominant room mode frequencies. Get a few big ones first and obtain more little by little, you will know when you have “almost enough” if you add more little by little. You might not need a vast amount of bass traps to reach a usable “compromize”.
Check and double check your monitor placement, and the angles of the speakers. Distance from the walls and the distance to your listening position are critical parameters to consider when looking for best monitor placement. If you are not using dedicated speaker stands, maybe check if you can get a pair of isoacoustic speaker stand to demo in your studio. If you are using dedicated speaker stands, check to see if the pipes on them are hollow - if so, fill them with sand/gravel.
I’m not an expert on acoustics by any means, but things outlined above have helped to get our project studio room to a usable “compromise” without investing a crap ton on acoustic treatment. Have bought one expensive pair of soffit bass traps though, but ATM don’t feel an immediate need to buy more.