three piles: save, donate/sell & recycle/discard.
Anything which is broken, unusable goes immediately to the recycle/discard pile.
The donate/sell stuff needs to actually get out of the house, otherwise it might find its way back to your mess. To facilitate this, pre-book a charity to come by for pick up a month after your clean up begins.
Once you've done your initial purge, take a hard look at your keep pile. Winnow again - Do you have multiples of a thing? How many black sweaters, stress balls, casserole dishes, cordless drill sets does a person need? Are you holding on to something for sentimental value? Can you take pics of your childs' favorite toys and store those in an album rather than holding on to all the toys themselves? Are you really ever going to use it again? That ice cream maker that you bought at the clearance sale two summers ago is still unopened in its box (yes its perfectly good, but not doing much for you, is it). Aim to reduce another 50%.
Organize the remaining goods. Date mark them, so if they don't come out of circulation every year, they get put to the save, donate, trash scrutiny next year.
resist the impulse to acquire more stuff.
realize that stuff doesn't make your life richer, just full of more stuff.
good luck to you and yours.
F. B.