I think it takes a while to get into the proper mindset. As a staunch Kondo follower I will give you, what I have found the 3 most useful tips which have kept me clutter free for 3 years.
the same thing in the same place is really useful. Especially when I discovered that my very healthy DH had 7 bottles of cough mixture all the same. All with one or two doses taken out. Also scattered around the house, were enough remedies to start a pharmacy. Now we have one small first aid box.
It is ok to buy storage but go back to it every 6 months as the process will make you stronger. I bought a pretty box for stationery. We had various writing pads, loads of envelopes, staplers, staple removers, various clips, a hole punch and files. I stored them In a beautiful box, but never used any of the contents. The box just made tidier clutter. At first I could not throw all the stuff out, but later came to realise I needed only 1 pad and a few envelopes. This stuff had not been used for years. The pad and envelope that was saved has not been used for 2 years, but it takes up so litttle space.
Finally, and I should have put this first, download and print the 200 Marie Kondo declutter list and put it somewhere prominent. No one who runs a home and works and has a life can possibly follow the book religiously. Taking every item out of your wardrobe takes forever. Find a small category from the list and work on that. It gives you an unbelievable sense of achievement. The space it frees up is a joy to behold. Gradually you get better and more ruthless and it becomes a joy not a chore.
My favourite place in my whole house is my cupboard under the stairs. Every time I open it I get a smug self satisfied glow over me.