Google Drive lets you organise your stuff by creating folders. You can have nested folders too, i.e. folders can contain other folders.
But did you know that you can also colour-code your folders to make your life easier? In the Google Drive interface, just right-click on any folder, then choose Change Colour in the pop-up menu, and select your colour by clicking on a swatch.
UPDATE: Where you have a file saved in multiple folders (didn’t know you could do that? See this post) the folder names will show up in the appropriate colours: