Use colors liberally to associate files and folders with certain ideas or categories. For example, if you're going through a divorce or doing your taxes, label all divorce- or tax-related files with the color red. By associating red with anger and indirectly with divorce or filing taxes, you'll remember what all your red files represent.
For help with finding files again, label files and folders with certain colors that represent emotions or ideas, and then type those same emotions or ideas as Spotlight comments. Now if you forget that the color red represents anger, just type anger in the Spotlight search box and Spotlight will find all your divorce- or tax-related files that you associated with anger.
Think of colors and Spotlight comments as just one more way to identify and find files and folders again. Since it's so easy to store files and folders, but not as easy to find them again, using colors and Spotlight comments can help you keep a little bit more organized.