Comment by ofalkaed

It is all essentially guess and check unless you want to learn acoustics, short of that the best you can do is search for what people have done in a similar situation. Dimensions of the room and what you are recording play a big role, reducing echos for recording a full drum kit is a very different thing than reducing echos for a single person recording narration for their youtube videos, for the former you will likely need full room treatment, for the latter just treating the wall you face or even rearranging the room may be enough. Changing mics could also do it, a highly directional dynamic pointed right at the source and up close will pick up less of the room than an omni condenser. Are you even recording or are you just trying to make you living space quieter?