There is a lot to think about when shopping for or using a carpet cleaner, such as how much space you'll need for storage and whether you should rent or buy. Here are some tips to keep in mind.

Carpet cleaners are heavy and bulky, especially when filled with water. They can be harder to maneuver than regular upright vacuums. They will also need quite a bit of storage space.

Tackle stain-causing spills immediately. Most households only need to wash carpets once every six months to a year, but spot cleaners are ideal for treating immediate spills, plus they're easier to store and use.

You likely won't use a carpet cleaner often, so it's OK to consider hiring professionals to do your whole home, especially if you have limited storage space. (It also can depend on how dirty and stained your carpets are.) Look at options for renting a machine from local businesses or retail stores like Home Depot. You'll be able to get the benefits of a commercial-grade cleaner without paying a fortune. 

Clean your carpet before you use a carpet cleaner. This may seem counterintuitive, but you don’t want dirt and hair to form wet clumps that block the cleaner. And if you haven’t washed your carpets in a while (or ever), be prepared for an embarrassing amount of hairy clogs to fill the dirty water tank. 

The carpet shampoo or detergent you use is important. Manufacturers often insist you use their brand, and while other types may work fine, you might void your warranty (although I have no idea how they'd know). Most carpet cleaners come with some detergent, but I had a good experience with Rug Doctor's Commercial Carpet Cleaner ($20). It works well and does not have a strong scent, and you can buy a large jug for cheap.

Try, try, and try again. It can be disappointing to fire up a carpet cleaner and find that it’s incapable of removing that old red wine stain or ground-in toothpaste. Don’t lose heart. Multiple cleaning sessions can sometimes chip away at established stains, and at least reduce, if not remove, them.

Drying your carpets can take a long time. Most carpet cleaners have different settings, and they will suck up some of the water, but they all leave carpets a bit damp. The deeper cleans tend to leave carpets wet, so think about how you might speed drying time. Use fans, fire up the heating, or do your carpet cleaning in the spring and summer months when you can leave windows open.

Protect your hearing. Of all the ways you can damage your hearing, a carpet cleaner is perhaps the least fun, so protect your ears. Some of these get very loud, so wear earplugs while you work.