When preparing formula, follow label directions exactly and instruct caregivers to do the same. The Food and Drug Administration says to boil cold tap water for a minute before mixing with formula, but whether boiling is necessary is controversial. Your best bet is to follow the formula manufacturer's instructions exactly, and to ask your pediatrician which type of water to use. Your pediatrician may say it's OK to use sterilized bottled water (check the label to make sure it says it's sterile). All bottled water must meet strict standards for tap water established by the Environmental Protection Agency. But if the bottled water doesn't say sterile, you'll probably need to boil it.

If you're using powder, the FDA now recommends reconstituting immediately before feeding your baby rather than making several bottles at once, although some manufacturers' instructions will tell you that prepared bottles are fine as long as they're consumed within 24 hours. You may want to get your pediatrician's take on this as well. For liquid concentrates and ready-to-feed products, the FDA advises consumers to follow manufacturer's storage instructions.

If you use different brands of powdered formula, don't mix up the scoopers. They may hold different amounts.

Don't heat breast milk or formula in the microwave, which can create dangerous hot spots. Instead, warm up bottles under running hot water or in a pan of water that's been heated on the stove for a few minutes. Shake the bottle before serving to even out the temperature, and test the formula or breast milk on the back of your hand. If it's lukewarm, it's ready for your baby, although your baby may be fine with cold breast milk or formula, too.

Never try to stretch formula with extra water. Improperly diluted formula can cause malnutrition and water intoxication, which can be life-threatening. On the other hand, too little water can cause diarrhea or dehydration and will give your baby more calories than she needs.