Do I need to do more for my dryer than clean that little pull-out lint c putting them in the dishwasher?

Most of us learned how to use a washing machine or dishwasher in our parents’ house many years ago and haven’t really changed our methods, even though most appliances have evolved radically since then. We rarely, if ever, read the manuals when we buy a new one or glance through the instructions on the box of detergent or bottle of dishwashing liquid.

But because we’re probably using these appliances incorrectly, our dishes and clothes may not be coming out as clean as they could be. And we may also be damaging the machines.

Let me start with soap. The No. 1 sin, according to repair people and appliance experts, seems to be adding too much soap to washing machines or dishwashers.

“Nobody thinks they use too much soap,” said Vernon Schmidt, who has been a repairman for almost 35 years and is the author of a self-published book, “Appliance Handbook for Women: Simple Enough Even a Man Can Understand.” But apparently most of us are in denial.

Washing machines and dishwashers are made to use far less water now than older models and, therefore, need less soap. And detergents have also become increasingly concentrated. So a little goes a long way.

“Most people use 10 to 15 times the amount of soap they need, and they’re pouring money down the drain,” Mr. Schmidt said.

Following the instructions on the soap container is a good first step. Christina Saunders, a spokeswoman for Procter & Gamble, which makes Tide, Cheer, Gain and other laundry detergents, said researchers at the company did thousands of loads of laundry to determine the right amount of soap needed.

She said the caps were changed on liquid detergent containers a few years ago to make the lines specifying amount of soap needed for different size loads easier to see.

Mr. Schmidt, however, argues that depending on how hard or soft your water is, one-eighth to one-half of what is usually recommended should be adequate.

Too much detergent can make your clothes stiff and shorten the life of your machine. An excess of soap can also cause a buildup of mold and mildew, said Jill Notini, a spokeswoman for the Association of Home Appliance Manufacturers, a trade group.

With high-efficiency machines — which includes all front-loading machines and any top loader that specifically states that it’s high efficiency — it’s a good idea to use detergents specifically made for them, she said. The detergents usually have H.E. on the front of the container. But don’t expect to see a lot of soap action.

“If people see suds, they think their clothes are getting clean, but that’s wrong — it means you’re using a lot of extra detergent,” Ms. Notini said.

Here is Mr. Schmidt’s test to determine if you’re oversoaping. Take four to six clean bath towels, put them in your front-loading washing machine (one towel for a top loader). Don’t add any detergent or fabric softener. Switch to the hot water setting and medium wash and run it for about five minutes.

Check for soap suds. If you don’t see any suds right away, turn off the machine and see if there is any soapy residue. If you see suds or residue, it is soap coming out of your clothes from the last wash.

“I’ve had customers that had to run their towels through as many as eight times to get the soap out,” Mr. Schmidt said, who lives in Indiana. He offers other handy advice on his Web site, refrigdoc.com.

Too much soap is also a problem in dishwashers and can cause dishes and glasses to look filmy. Again, check the detergent container for recommended amounts — you definitely don’t have to fill up the entire soap container in the dishwasher.

Also, if your plastic items come out still wet, that doesn’t mean your dishwasher is not doing its job. Most dishwashers today emit less heat than the older models, so plastic doesn’t dry completely.