What's the best way to drain the master cylinder on this car?
I usually just suck out the old stuff from the reservoir using a vacuum pump (turkey baster will do). Be careful not to stir up any sediment though as this could get into the system. Fill it up again with fresh fluid (brake fluid sucks moisture from the air so make sure you buy a new bottle). Bleed the brakes until the fluid is the same color as in the bottle (or at least close). That's about it.