The most important rule: Always maintain frozen food below 0°F.

• Quality deteriorates if stored, even temporarily, above 0°F.
• For each five degrees increase above 0°F, for some high moisture products like seafood, the life of a frozen food is decreased by 50%.
• Frozen food will last a year or more if stored below 0°F.
• Have a thermometer in each freezer. More than one helps detect "hot spots" and temperature variations.
• Avoid:
  • opening freezer doors unnecessarily.
  • adding non-frozen items to the freezer - they warm frozen items and can transfer flavors.
  • staying in the freezer longer than necessary - a warm body can dramatically increase the freezer's temperature.
• Freezer cold curtains also help maintain temperature.
• Choose a reliable accurate (+/- 1°F.) digital or instant read thermometer with a short response time.
• Calibrate it by immersing it in melting ice (32°F).
• Before recording a temperature, pre-cool the probe by inserting it between two packages of frozen food and wait for a steady reading.