When you are cleaning any spill in the carpet, be sure never to rub a carpet to soak up liquid. Keep using dry parts of the cloth and a blotting motion for best results when you have any spill.
When you are trying different types of cleaning on your carpet be sure to let the carpet dry completely between treatments so you can see if the color or stain does lighten at all.
For a quick pick me up of those old and tired looking carpets - sprinkle a bunch of salt over the whole carpet. When you
vacuum the salt is going to loosen and bring more dirt up that you might have gotten before!