Oh god I constantly have the sliding puzzle problem. this year on mat. leave is the year I kill the piles stone dead. The solution is not more space, it's less stuff. So don't bother buying more and more fancy storage thinking it will solve all your woes- it will just hide the evidence of your problem and you'll keep on accumulating stuff until you run out of space.
You need to decide what furniture you want to have in your house. Then decide what is going in each piece. Some things are a given: you need decent storage for bedding and towels, cleaning materials, kitchen equipment, etc. After you've dealt with essentials you can decide whether you have room for anything else!
Sort those categories out first: only keep what you need, and arrange your storage so that it is only 80% full by either selecting a large enough cupboard, or getting rid of things until it all fits in. You need that spare 20% empty so that when you need to put something away, you can do it easily, because if you have to take five minutes to re-stack your towels to fit another one in I guarantee you won't bother.
Then move onto more frivolous stuff. How much makeup do you realty need? How many pairs of shoes? If they are shoved in the back of a cupboard you've probably forgotten you even own them...
Personally:
I have a loose rule that if DD wants to keep it, it has to fit in her existing storage. She has a good sized room to herself, so I think this is fair. I hope that I will be able to teach her not to hang onto things she's finished with.
I decided last year that I don't have the space for paper books. So I'm waging a war on my shelves to replace the dead trees with electronic versions.
I also decided to get real about a couple of hobbies and collections I have. I'm never going to use up all the materials I have, so I've got rid of loads. I don't have the space or inclination to display my red glass collection, so that's going soon- it simply isn't earning its space. I have too many cookbooks- the ones I have never used and don't even flick through for inspiration are on the hit list.
I read quite a few de cluttering blogs. These helped me realise that the value of my living space was, in the main, much higher than the value of boxes of stuff I never looked at (because there was no space to be able to enjoy it!) Things I'd hung onto for sentiment's sake were meaningless in that owning the object didn't mean I kept the memory any fresher- but shoving cards from my wedding in a damp loft meant that they got spoiled (so weren't a nice reminder) AND took up useful space.
On getting rid of things: the shops are a wonderful storage facility. For hard-to-find 'vintage' things: we now have the Internet. Almost nothing is irreplaceable.