Carpet cleaning can be something of a nemesis. If you're renting, you can bet your bottom dollar that you're going to have to clean that carpet - possibly by hiring a professional cleaner or by getting in one of those steam cleaning machines - when you do the final tidy up before moving house. And if you're not renting, well, you probably want to keep your carpets in good nick because the house is YOURS and you can't blame anyone else for grotty threadbare carpets. Anyway, carpets can be a pain to clean, no matter where you live, mostly because they continually have feet marching all over them and those soft, fluffy fibres trap dirt.
You could, of course, do without a carpet and leave some areas in your house with polished wooden boards warmed up by the occasional mat. However, you will find that this allows more dust to fly around the place and you will need to wield the duster that little bit more often.
Tips for cleaning carpets and keeping them clean:
Provide decent doormats that actually scrape bits of stray mud off at both your front and back doors and stop a lot of the dirt getting inside in the first place. Encourage children (and other family members) to have "outdoor shoes" that never come inside. Have a place for folk to change into and out of these shoes near the door, and allow for plenty of space to store Wellington boots, rugby boots, gardening clogs, etc. Take a tip from Asian culture and remove all shoes at the door. This is becoming more and more common. Going barefoot on carpet is a sensual delight, and if it's chilly, wear thick socks or a good pair of slippers to keep your toes from freezing.
Vacuum frequently - weekly is the bare minimum.
Treat all spills, stains and smears as soon as possible after they occur to stop the dirt "setting" into the fibres of your carpet. In many cases, you don't need a fancy carpet cleaning products - flooding the spot with fresh water (but make sure that the stain doesn't spread everywhere, which it will if you use too much) followed by blotting with a thick towel.
Really nasty patches of dirt can be cleaned using natural cleaning methods. The very best is... warm soapy water. Don't use hot water - you may have a bit of protein-based material in the ick that you're trying to clean, and hot water will set this stain in. Use a medium-stiff scrubbing brush (harder than a toothbrush but softer than what you'd use for scrubbing a tile floor - if you have a brush you use for scrubbing clothes, use that). Make the soapy water foam - this lifts the dirt up and away.
While soapy water is good for cleaning carpets, don't use too much and get the carpet absolutely flooded. Too much water will take ages to dry, and while the water's down there, it will attract more dirt and make a happy home for mildew. The best way to apply the warm soapy water (or any other carpet-cleaning product, home made or otherwise) is to dab a scrubbing brush into a bowl or bucket of the liquid, then letting the excess drip off before scrubbing the surface of the patch to be cleaned.
It's best to hire a cleaning machine from a professional company for cleaning large areas of carpet. These days, you'd be mad if you tried cleaning a whole room of wall-to-wall carpet by hand with a scrubbing brush. Honestly, you have better ways of spending your time!
Some experts recommend using a broom to sweep over the area of carpet to be cleaned to lift the pile of the carpet and allow the trapped dirt out. You can get a similar effect by using your scrubbing brush dry on the spot before applying the warm soapy water. But use the broom for a once-over if you are cleaning the whole carpet with a steam cleaning machine.