Cleaning is just one part of it. Tidying up is just another.

The real part is you have to constantly be running a background process (to use a computer term) of throwing stuff away. Either garbage, or goodwill, or thrift store, whatever. If Stuff In > Stuff Out over any given period, your house will get full. You may not see the clutter, but every closet and cabinet will be filled.

Cabinets and storage areas should have 10-20% empty space, so there's always room to put something in a hurry. If they're all crammed and you go in there seldom, it probably isnt stuff you "need"!

I learned from watching my father...he was constantly throwing out stuff. We always thought he was out of line, but he kept the house from getting too full. He has backed off in the past few years and my parents really have some cleaning out to do. Mom is a level-1 hoarder (just a level 1, no biggie) but its there.

You have to learn to part with things, to be comfortable with that and not always wondering "I could use this one day!"

Two things have made a big difference in our home. First, kids have specific places for their everyday type clutter (backpacks, school stuff) and it is their responsibility to make sure those things are put where they belong. Second, I cut my shopping of anything other than groceries/cleaning supplies by about 99%. I "thought" I had cut down before then, but going cold turkey, an in absolutely nothing new, really helped with our clutter situation.