Sometimes material things aren't what you need for the perfect space. Changing your perspective can be difficult, but it's necessary for having a nicer, cleaner and better looking house. Think of your space like your body, if you get your hands dirty, you don't wait til the next day to clean them. The same mentality should apply to your house. Everybody dreads the weekly or monthly clean up, but just little steps along the way can make a massive difference in the amount of mess there is to clean up. If there's less mess, it's easier to appreciate the design of your house- and you'll feel more comfortable and relaxed in your surroundings because you're not constantly unconsciously reminded that you need to clean up. Try it, let things go that you no longer need and have more free space for new stuff or even for old stuff that previously went on the floor!
Start in each room and remove every item apart from furniture. If you feel like the atmosphere of the room has changed, or you feel less at home after removing a particular item, put it right back and get going with some more decluttering. At the end, you may find you have tonnes of extra bits and bobs that actually don't add anything to your home and do nothing but clutter up the space. It can not only help you feel better knowing everything in your house is there for a purpose and improves the space, but it's also a good reason to avoid excessive purchases and keep costs down. Apply the same mentality when buying something, will this add something to my home?