I read the Marie Kondo book several years ago and enjoyed that too but never quite managed to complete the process. Dana (A Slob) is much more realistic in that sense; she explains decluttering as a maintenance chore rather than a one off project (though it can be somewhat of a project at first). This is helpful to me, as I had not previously seen it that way.
However some things that I took from Marie Kondo which I do use:
Store things in such a way that you can see everything all at once, and don't need to dig under items to get other items out. If you have to move item A to get to item B, it's likely that item A will get left where it is and it will look messy. Her solution to this is to stack everything vertically, like books in a bookcase. It's not the only way; visibility and accessibility without making a mess is the key.
Store things near to where you finish using them, not where you start using them. The logic behind this is that if we want something, we'll put effort into getting it, but if you have to put effort into putting something away you simply won't. I think this is actually key to a lot of human behaviour - we ascribe morality to things (It's the right thing to do to put something back/it's a lazy or arsehole thing not to) - have you seen that meme about how returning a supermarket trolley is the ultimate test of whether someone is an arsehole or not? I think that's incorrect - you rarely ever see trolleys abandoned right next to a corral. My guess is that if you provide more corrals, people put their trolleys away, and distance from the nearest corral is likely the most effective predictor of whether or not people will return trolleys. If you want to encourage a behaviour (including in yourself), think about what's difficult about it and reduce/remove that or make it easier in some way. If you want to discourage a behaviour, put something in place that makes it more inconvenient (e.g. Aldi does not have loads of trolley corrals, but they charge you £1 instead.)
I also use that previous one in reverse ie I put my guitar where I can see it when I'm listening to music, which makes me more likely to pick it up and play it. I put the kids' books where they can see and reach them so they are more likely to bring one to me and ask to read.
If you love something and you have decided to keep it, don't hide it away in a drawer, find a way to display it so that you can see it regularly and it will make you happy.
Use the "good china".
Think about the purpose of your rooms and what you want your ideal life to be and how you can use your rooms/house to support that.
If you're hanging onto stuff "in case I need it later", rather than focusing on the money saved in buying that item later, contrast the effort/cost in replacing that item when you need it later with the space you'll gain now (especially when multiplied over 50+ items that you might later only need to replace one of). Consider this cost as like "renting space" for the shop to store the item for you in case you need it later. (This was such a game changer for me. I am yet to convince DH, who thinks that it's more economical to spend money on crates from Ikea to store all the cables that we might need one of later and he'll probably buy a new one because it will be old by then anyway.)