Always have an O2 tank on board- never know when we might need to go higher
during a long cross country. Although not required by reg, for prolonged
flight at around 10k or higher I always use it to keep my O2 sat at or
greater than 92%. I find that flights become a lot less tiring and I feel a
lot better. Flying at night it definitely helps the color discrimination and
night vision.

Agree with the recommendation about doing a chamber ride- it is a great
experience and worth the time and trouble of arranging. (of course, being in
the Air Force I don't have an option)