(1) Check for leak by blockage and gently inhalation each time mask is
removed and replaced.
(2) Check oxygen flow indicator at regular intervals. Also, CHECK COLOR
OF NAILS AT REGULAR INTERVALS -- if blue above 20,000 feet turn Auto-Mix
to "OFF" position.
(3) Check oxygen pressure gauge frequently.
(4) If temperature is below freezing, manipulate mask to free it of ice
at regular intervals. Wiping moisture from mask periodically will
prevent freezing of mask.
(5) Open EMERGENCY flow only when absolutely necessary ... notify pilot.
(6) Over 28,000 feet switch Auto-Mix to "Off" position ... turn back to
"ON" position below this altitude.
(7) Re-fill walk-around bottle frequently when you are using it at
altitude.
(8) Avoid unnecessary exercise above 20,000 feet ... take your time!
(9) Observe your fellow crew member at frequent intervals above 20,000
feet. You can recognize before he can if he's in trouble.