Thanks Bruce! I love this thread :-)
Really, really, really think about how much stuff you need. If your house was burning down - what would you take (and could you find it?!). And be careful about what you bring into the house too. There's a lot of stuff you just don't need.
One final tip for kids' stuff. Keep a 'small toy' box for each child. Put every kinder surprise, happy meal toy, party bag toy, stuff out of crackers etc. into that box. You can include some small things that are otherwise homeless e.g. yoyos, card games, small binoculars, magnifying glasses etc. Occasionally they will pull it out and have a good play. Occasionally you can also sort through it and thin it out a bit. This stops a LOT of clutter in the kids rooms!
OK - one more. Those cylindrical baskets that you hang from the ceiling for teddy storage. Game changer!
And another - if you are buying clothes, buy a few things that match all at once. (I know MN will say you should be trawling ebay and charity shops but some of us are OK with new - actually I receive handmedowns so it's not all bad). So get 4-5 t-shirts, a couple of jumpers, socks and shorts / trousers etc. that all match. You can get away with having a LOT fewer clothes that way - less to wash, fold and store.