we have just decluttered after an extension (yes, wrong way around).
we didnt bother before starting and we shifted stuff from over crowded rooms into the living room, box room and conservatory. it was awful and we looked like we lived in a second hand shop sorting room with jumble and piles of paper.
its taken us about 2 months using the weekends to sort and take to our local council recycling site and dump.
we've got a small house and its taken us years to realise that we just cant't house as much furniture in our house as we'd like to. so we've taken things like coffee tables, lamp tables, bookcases, tonnes of books, old lamps that are dated etc to furniture recycling.
my house isnt like a show home but it has about 40% less clutter than before.
it also feels like cleaning is getting easier with less stuff and i feel more motivated now there is not as much stuff on the floors and shelve units.
we still do have a whole host of crap taking up space like a bulky high chair, airing rails to dry indoors when needed, tiny bits of barbie and lego, school bags/letters/paperwork... but its better than before.
im going to do that oraganizing made easy thing where in addition to picking up after the kids/dishwasher/putting away laundry, im going to do 15 mins daily of extra cleaning.