"Nothing is more common on earth than to deceive and be deceived," said the 18th century German author Johann Seume. Seume would feel right at home in today's world where, thanks to the Internet, money-making seams have reached global proportions, netting fortunes for online hucksters whose ploys, although often quite obvious, nevertheless find plenty of gullible victims.

But life without a computer is no cakewalk either. Rip-offs, bogus deals, and consumer headaches are all around us. They range from shady (but not actually illegal) practices commonly referred to as "tricks of the trade" to full scale frauds in which identity thieves purloin our very names and reputations through access to our bank cards and Social Security numbers.

How can we protect ourselves? The first step is, know the enemy. In his new book, Scorn Proof Your Life, investigative reporter Sid Kirchheimer reveals many of the surprising ways we can be deceived when buying a new car, lying in a hospital bed, sending a check in the mail, or standing in a checkout line. Kirchheimer has gone straight to the horse's mouth, interviewing ex-con men, ex-burglars and even ex-car salesmen to find their trade secrets. Here is a sampling of the common seams and rip-offs Kirchheimer alerts us to in his book.

NAME-MAPPING
Paying your bills is a good idea, but putting that check in the mail can be bad for your financial standing, especially if you mail from a home mailbox that might be plundered by thieves looking lot freshly written checks like yours. Thieves can easily cover your name with tape and wash your check in a solution that dissolves the amount, leaving a blank check for them to write whatever they want with your name on it. One solution is to write checks with a special $2 pen manufactured by Uni-Ball that makes your writing on checks indelible.

Having your identity stolen by someone gaining access to your Social Security number, checking account details, or driver's license can be a very bad experience that leaves your credit rating in a shambles. Although identity theft is frequently linked to online transactions, only about 13 percent of eases involve Internet accounts. Some 8 percent result from stolen mail. Another 3 percent come from dumpster diving to find checks and receipts you have carelessly thrown away. It's best to shred all incoming mail that contains information such as your name, address, account information and Social Security number, especially convenience checks and new credit-card offers.

Also be wary of those too close to you in a checkout line. They may have eagle eyes eager to learn your PIN number. Likewise, don't use casual clues such as your birth date or your mother's maiden name for passwords or PIN numbers for bank cards. Thieves are adept at gleaning this information and using it to break your account code.

Also, don't use auto mated bank tellers if you see any unfamiliar equipment attached; it may be spyware designed to steal your personal information.

TELE-PHONY CHARGES
Have you looked at your phone bill lately? Doing so could save you some money. Close examination may show you are being billed a "home wire maintenance" charge of $2 to $5 every month. This is actually an insurance charge against a costly repair to lines inside your house, which statistically is almost never needed. It's simply cream off the top for the fat-cat phone companies.

When you need to find a number outside your area code, do you call 555-1212 for information? If so, you are being charged for the service at $1.25 to $3.49 per call. It's less expensive, the author suggests, to call the local assistance number, 411, and have them look up the number for you.

AUTO BANDITRY
When car shopping, beware of bogus charges. You may find these on the window sticker in the dealer's addendum to the manufacturer's suggested retail price (MSRP). One phony charge is "Dealer Prep." According to the author, you should never pay this charge. Dealer prep is included in the MSRP, so you are being charged twice for it.

Don't believe you are getting a deal if the salesman generously concedes to knock off the "market value" charge on the car, if there is one. Such charges are supposedly added to a car that is a hot seller and in higher demand. They are really there just to make it look like you are getting a deal, but you're actually just paying full price, which is a great deal for the dealer.

Dealers always want you to hop in the car for a test drive first thing. Put that test drive off until later. While you are driving, the dealership will use your driver's license to pull up information on your credit record and previous car purchases that may put them at an advantage in price negotiations. When you arrive, don't even give them your last name, the author recommends, until you are ready to negotiate.

HOME RIP-PAIRS
Renovate your home to live there, not to sell, the author advises. A new $60,000 kitchen won't add $60,000 to the sale value of your house, and if you are in the wrong neighborhood, it won't add anything.

Unfortunately, home-improvement contractors have a reputation that rivals that of car salesmen, but there are good ones. The trick is to sort out the good from the bad. The good are generally found by word of mouth from friends or family. The bad are generally the ones who contact you looking for work.

A good source of information on contractors is the local building department at city hall. There you must understand the home inspector's terminology and body language. If he rolls his eyes at the name of a contractor, enough said. Also if he cites a "policy" of not commenting, that also means don't hire the bums.

Never sign a check for contract work. Sign a contract. Because many contractors may take much longer to do the job than expected, it is a good idea to add an extra week to the contract period in return for a line stating that if the job is not done in that period, 20 percent will be deducted from the bill. That will provide plenty of incentive.

ROAD RIP-OFFS
Ready for a nice vacation? Offers of "free vacations" that come in the mail or e-mail are not the ticket to Shangrila. To claim a free vacation, you will probably have to pay a processing fee that exceeds the cost of the vacation.

Similarly, memberships in discount travel clubs offering reduced-rate certificates for travel may not get you very far. The certificates are generally difficult to redeem and probably have limited redemption dates.

Offers of travel agent "credentials" that claim to give you access to travel-agent perks are probably bogus and will not be recognized by travel-industry operators, airlines, or cruise lines. Also, if any offer of reduced rates seems too cheap to be true, be sure to read the small print--all of it.

Once you have reached your destination, and even while you are on your way, keep tabs on your wallet or purse. A former professional pickpocket recommends that men keep wallets in a breast pocket or a tight jeans pocket. Loose front or back pockets are vulnerable for being picked, and wrapping a rubber band around your wallet will only make the job easier.

Women should sport a handbag that straps diagonally across the chest with the purse just below the underarm, The strap should be wide so as to be difficult to cut with a knife and prefer ably have locking closures.

Don't carry a lot of money with you, but do carry a throwaway wallet with a few dollars and old hotel key cards, especially at night. If accosted, toss this wallet to the muggers and take off.