In my experience GadgetFreak's suggestion--fly with the cartridge/bladder as full as possible--and reasoning--air expands, liquids don't--are both right. Do that and I think you'll be in good shape.

I personally use a Namiki/Pilot Vanishing Point pen, which is a retractable fountain pen, which I highly recommend. It sounds a bit odd, but works like a charm and is very nice to write with. Plus retracting it prevents the nib from drying up, which I find very useful at meetings where there are long gaps between writing.

Thanks,
Alex