If you don't own a steam cleaner, renting one and dragging it home to clean your carpets can be a pain. Plus, you have to do the deed, then wait for the carpet to dry. If you don't have time or funds for all that, you can freshen up your in around an hour with a few low-cost items you probably already have around your home.
Remove stains with a blast of foam
First, your carpet probably needs a spot-clean. An easy, low-cost solution to get rid of carpet stains is shaving cream. Spray the stain with some foam shaving cream (not the gel kind) and let it sit for 30 minutes. Then, blot it with a clean cloth. This solution works on a wide range of stain types, including grease. Before you tackle the stain, do a test patch in an inconspicuous area of your carpet to ensure it won't cause any discoloration.
Freshen up with some baking soda
Next, sprinkle a liberal amount of baking soda on the carpet and let it sit for 10 minutes. How liberal? You'll need around one box of baking soda per 10 by 10 feet (3 by 3 meters) room.
The baking soda will absorb odors and cling to dirt particles, making them easier to remove. After the 10 minutes is up, just vacuum like normal. Your carpet will be extra fresh and looking clean.