Do the rules of acoustic treatment change when the room is small? If so, how can it be adjusted correctly to my situation?

I'm currently looking to do a few things in my (very awkwardly) shaped closet. So, I've been struggling with going back and forth between moving blankets, auralex foams, etc. Seems like whatever I encounter, there is somebody on reddit who makes a commet about it being a bad solution and to get GIK. Only issue, is I don't have the kind of money for that, and I'm not particularly handy when it comes to building things like rockwool panels myself.

Thus, I started realizing that maybe these pieces of advice are different depending on specific situations, which is why there are such mixed opinions. My main goals are:

-Voice overs / Voice acting

-Recording instruments

-Singing

Does anyone know what can be done to taylor to my current situation? Thanks in advance.