Another thing I can't emphasize enough.

Be EXTRA polite to staff, especially if you're a guest on another airline. You are effectively representing your fellow 'visiting team' and fellow Non Revs, and gate agents have a looooooooong memory!

Some gate agents *HATE* non revs. I've seen 'the look' from gate agents of my own airline go sour when they find out my status, and one was a real dragon! But after a few trips where I just smiled, shut up and minded my manners each time, she eventually really warmed up - I've even got comp upgrades to first on some flights now.