Tidy by category, not by location
One of the most common mistakes people make is to tidy room by room. This approach doesn’t work because people think they have tied up when in fact they have only shuffled their things around from one location to another or scattered items in the same category around the house, making it impossible to get an accurate grasp of the volume of things they actually own.
The correct approach is to tidy by category. This means tidying up all the things in the same category in one go. For example, when tidying the clothes category, the first step is to gather every item of clothing from the entire house in one spot. This allows you to see objectively exactly how much you have. Confronted with an enormous mound of clothes, you will also be forced to acknowledge how poorly you have been treating your possessions. It’s very important to get an accurate grasp of the sheer volume for each category.
That is from Marie Kondo, Spark Joy: An Illustrated Guide to the Japanese Art of Tidying, a recommended book. Also never tidy the kitchen first, do not keep make-up and skin care products together, and “…the first step in tidying is to get rid of things that don’t spark joy.”
I have a related tip. If you want to do a truly significant clean-up, focus only on those problems which are not immediately visible. This will help you build efficient systems, and prepare the way for more systematic solutions to your clutter problems. You’ll then be prompted to take care of the visible problems in any case. If you focus on the visible problems instead, you will solve them for a day or two but they will rapidly reemerge because the overall quality of your systems has not improved.