Like a spy, once you start an affair, you need to monitor every little move you make to keep your secret hidden. There are no guarantees when you choose to cheat, so be prepared to face the consequences.
Use an anonymous email service to communicate with your lover. Yahoo or Hotmail both allow you to check email messages without leaving traces on your computer. Don't use the handle "Secretlover" in your email address.
Confirm that your spouse cannot monitor your phone calls. Most cell phone companies provide an itemized list of your calls, both on paper and online, and you don't want these incriminating details to fall into the wrong hands. Use the tried and true stand-by, "The dog ate it," if your spouse asks to see the bill.
Have legitimate excuses available for the extra mileage on your car. A visit to a sick grandma, perhaps. Having a hidden affair with a co-worker is better, since you don't have to drive anywhere to meet.
Make extra money, maybe selling your prized cat figurine collection, so you'll have plenty of cash available to spend on your secret lover without making withdrawals from the family bank account.
Buy your lover only the same perfume or aftershave as your spouse. Your spouse may think it's their own scent on your clothes.
Keep the same old clothes. You will invite suspicion if you suddenly go from tidy whities to thong underwear.
Stay out of shape since a sudden improvement in your appearance is a sure sign you're cheating. Cosmetic improvements like a toupee or long, red fingernails are also taboo.