

The reasons that clutter makes us feel stressed are routed in our pre-history as a species, so you’re not going to be able to ignore a clutter problem in your home, no matter how much will power you have.
De-cluttering gets tricky because just as having too much going on around us makes us tense, having too little happening visually also amps up our stress levels. That means a blanket statement such as, “Make sure all countertops and tabletops in your home are bare and don’t put more than one photograph on top of your piano” are going to result in unhappy people.
Your design goal has to be to have moderate visual complexity, this means, that there is a comfortable amount of “stuff” happening around you visually but not too much—it is the Three Little Pigs story, translated to the design world.
But what is moderate visual complexity?
There are equations for calculating visual complexity levels exactly. They are incredibly difficult to use and so no one does so unless they’re working on a dissertation and have a picky advisor.
How people actually determine visual complexity is to look at an image with a known level of complexity and compare whatever space interests them to that image. This may seem impossible to do, but actually it is pretty straight-forward and people get the hang of it without much stress.
The sort of image you want to compare to is a residential interior designed by Frank Lloyd Wright. Look at the carefully curated sets of colours and shapes he uses and how he imposes some sort of order on those colours and shapes via balance, symmetry, rhythm, etc., then take a look at your world and edit accordingly. Shapes can be in patterns in rugs, upholstery, and wall papers, but they are also found in the shapes of the arms of seats and ornaments in mouldings. Once you start to look for shapes it’s clear that our hold world is a collection of shapes.
When you’re reviewing your world and removing things form it (or potentially adding items to it), it’s important to put the things you pare away from tabletops, etc., out of view, in closets and drawers that can’t be seen into, that don’t have windows with transparent glass, etc. If you put something in a transparent container, you haven’t done much to reduce the visual clutter in your home.
Just as we prefer moderate visual complexity in the spaces where we find ourselves, we also prefer it in the art we use in those spaces, so select paintings, photographs, etc., accordingly.