For starters, you'll need a good digital thermometer, which you can find in drugstores for less than $10. Digital thermometers are easy to use, easy to read, and fast — most give an accurate reading in ten seconds to two minutes.

If you still have an old-fashioned glass thermometer around the house, you'll want to dispose of it properly. (Check the yellow pages of your phone book to find your local household hazardous waste site.) These thermometers can shatter and leak dangerous mercury.

Some digital thermometers are specifically designed for use in the rectum, but most can be used rectally, orally, or under the arm. (If you take your baby's temperature using more than one method, you'll want to designate a thermometer for each.)

Digital ear thermometers, called tympanic thermometers, are usually more expensive and can only be used in the ear.

That leads to the question of where to put the thermometer to get the best reading: in the rectum, the ear, or the armpit. (Taking your child's temperature orally won't be an option until he's a little older.) Each method has advantages and disadvantages, so talk it over with your doctor to see which method she recommends for your baby.

Regardless of which method you use, don't take your baby's temperature right after he's had a bath, as it could affect his temperature. Wait at least 20 minutes after bath time for an accurate reading.