Nice use of Pareto's law, i find that it applies to almost everything! I realised how much I didn't use most of my stuff when I moved abroad. I had some stuff shipped and had to deal without it for 2 months, and when it arrived I had completely forgotten what it was!
Needless to say I don't buy clothes anymore...
I also noticed when I moved flats... you much stuff I had to carry that don't serve me any purpose. What's your decision-making process to acquire new stuff now? I'm curious...
Now I find that I buy things from pure necessity. So I've learnt to be patient, try living without something for a while (e.g. I think I need new jumpers, but first I deal with just wearing the warm clothes that I have for a few weeks) then if I find that through necessity I absolutely can't live without something (all my jumpers are in the wash/aren't warm enough) then I buy it. I don't enter any shop without a purpose!