To ensure data integrity for your cassettes, follow these guidelines: 

• Do not touch the tape or attempt to clean the tape path or tape guides inside the cassette. 
• Do not leave cassette tapes in excessively dry or humid conditions. 
• Do not leave cassette tapes in direct sunlight or in places where magnetic fields are present (for example, under telephones or near transformers). 
• Do not drop cassettes or handle them roughly. 
• Do not stick more than one label onto cassettes; extra labels could cause the cassettes to jam in the tape drive. 
• Store cassettes in their plastic cases when not in use. 
• Do not let cassettes get dirty, and always stack the cassettes in a clean environment. 
• Do not use cassettes when the Caution signal is displayed by the cassette light, located on the front panel. The light shows a repeating pattern of green for 4.5 seconds, then off for 0.5 seconds. If this light pattern appears, it means that the tape heads need cleaning or that the tape is nearing the end of its useful life. 

Temperature considerations

The cassettes should be used only at temperatures between 5°C (41°F) and 45°C (113°F). You can, however, store them at temperatures down to -40°C (-40°F).

If you expose cassettes to temperatures outside the operating limits, stabilize them before you use them. To do this, leave the cassettes in the recommended operating temperature for a minimum of two hours. 

To avoid temperature problems, observe these guidelines:

• Ensure that the tape drive is in a position where the temperature is relatively stable, for example, away from open windows, fan heaters, and doors.
• Avoid leaving cassettes in severe temperature conditions, for example, in a car standing in bright sunlight. 
• Avoid transferring data (reading from and writing to cassettes) when the temperature is changing by more than 10°C (50°F) per hour. 

Source: http://www.docs.hp.com/en/B3813-90014/ch05s08.html