Well, the rules you apply are flexible. I do not stick to any of them BTW
1) Trash the old pots of paint, cement and sand, and that half used sheet of plasterboard and MDF at the end of a DIY project.
2) If the consumer electronics doesn't pack up within a week, trash the boxes that they came in. Who wants a loft full of empty cardboard boxes?
3) Keep just one pair of grubby jeans and one paint-splattered sweater. You only need one of each.
3) When you find that wierd plastic moulding/ screw/ piece of metal etc etc that you can't quite work out the purpose of, but might be vital at some stage in the future, trash that as well. You will not miss it.
4) Do not chuck out books or LPs.
5) Bin all interconnects from the hi-fi, TV, etc that came in the box, and were never used.
6) Keep all maps, but trash the brochures from the holiday.
7) Keep all photos.
8) Clean out My Docs, and your email on your PC.
Well, there you are, totally liberated...now the next problem is to persuade your partner to part with whole cupboards full of clothes and cosmetics that she started acquiring 30 years ago .
Good luck.