When I was decluttering, I worked on really conspicuous things like unused furniture that was in our living space first, and the contents of the basement later, the contents of the filing cabinets still later, etc. If you pick the most annoying thing in your life to improve first, you'll _feel_ so much better you will have the energy to improve the next thing.
But there will come a point where you start to feel like maybe you are polishing ... something that doesn't really need to be polished. You are spending more time being organized or efficient or whatever than you are actually doing work. If you are a really committed procrastinator (I am not <-- there are a bunch of people who have just peed because they are laughing so hard. When I say my sense of humor is weaponized understatement, I am not making a joke. Much.), you might _start_ spending more time on organization than on work, and not in a good way.
Nobody ever thought I was a very disorganized person, even when things were at their worst. People who saw the house the first couple years we lived here are still noticing things that we fixed months ago, because the change has been so dramatic that it takes a while to sink in. Nevertheless, there is still a sea of toys ... everywhere. That's because we have kids and we are big believers in toys. There are still projects in progress ... on most flat surfaces. That's because we have a lot going on. We have a lot fewer stacks of things that we're not going to do anything with, but we're not sure what to do with. Most of those have been eliminated, through filing, disposal, or appropriate storage until the next time we need it. A bunch of my more recent projects (such as buying things to make it possible to travel lighter -- I know, I know. Believe me, I know) have involved what I affectionately (really!) think of as "recluttering". Two ideals guide me: I want to be surrounded by things that make me smile, and energize me and comfort me, and I want my world to tick along as smoothly and as efficiently as it is worth my time to make it.
XKCD, to the best of my knowledge, has little to say about the aesthetics and psychology, but that comic is permanently taped to the wall to the right of my desk. Because it is really, really important to me to get that tradeoff right.