I may have bad/sad news for you: Letting go of clutter is not something that is ever completed, done, checked off, in a never-have-to-worry-about-this-again state. It is a process, possibly a practice or a habit one can develop.
When I got "Clear your clutter with Feng Shui" by Karen Kingston, I devoured it. But I had time to do that (or rather, I made the time to do it. Yes, it was more compelling than homework. C'mon! This applied to real-life!) I have tossed/gotten rid of/donated probably over 1000 lbs of stuff by now. (I haven't kept track of all the weight) but I do know that I dumped between 500-600 pounds of stuff within the first 3-4 months of having that book. Please note that I didn't toss everything out all at once. It really is an unfolding process. Here's a few examples of how it happened for me.
Let me set the stage first. I had moved into my own apartment (hallelujah!) more than a year prior. Most of my stuff was still in boxes lining the walls of my rooms in the same exact place they were set down when I moved in.
One night I was kneeling in my bedroom, about to say a prayer before hopping into bed. I looked at all the papers and junk lined up against the wall, and my eyes settled on a piece of paper--it was an old 'love note' from a former/ex-boyfriend. (One who had married by this point in time!) I picked it up and thought "Why am I holding on to this? Am I scared that no one else will love me ever again?" And I realized that that was exactly why I was holding on to it--to remind myself that someone loved me once, and to validate that I was loveable. After realizing this, I TOSSED IT! I knew (deep down) that I was loveable, and that somewhere out there I would find someone to love and who loved me. It was a relief to toss that paper and the emotional baggage associated with it.
The next day I read something in "Clear your clutter with Feng Shui" that basically confirmed my actions. We hold onto things out of fear, needing validation, reminding ourselves of something. It was nice to have that confirmation after I had already come to the conclusion myself.
I can recall moments when it dawned on me that certain large items (furniture pieces) in my apartment needed to go. But it was a slow unfolding process. Kingston mentioned that if you can't get rid of something right away, to at least try to move it to a higher place (to increase it's energy level). I started by placing all the papers and boxes in my bedroom into one pile (on top of a box). Then I eventually moved it out to the living room. I wanted my bedroom to be my Sanctuary. It became that. I noticed it when I started doing my homework in my bedroom on the floor--just because it felt so good in there.
That realization motivated me to begin to work on the boxes and piles in the living room. It took a while. But I will always love that apartment because I turned it into a Sanctuary and a haven. It was such a peaceful comforting place for me. Now I need to work on that process for this new apartment.