Good idea which someone taught me to prevent nose bleeds...
STOP PICKING YOUR NOSE!
if you still have problems...
Take a small amount of vaseline or lip balm on your pinky finger, and shove it up your nose, and rub it all around. Please do this in a lavatory, out of view of passengers.
\oh and please wash your hands.
Combine with drinking lots of water, at least 3 litres per 12 hour duty. yes 3 litres...
Avoid caffeine, except maybe a coffee after crew rest, and once again just before landing, to stop you falling asleep on your jump seat.
