Completely discharge a MacBook Air battery to conserve it?

Apple's site is unclear on this. What's the best way to maintain a battery so it doesn't die out after a few years? The Mac rep who sold me my computer told me to let the battery totally die out once a week, then charge it to 100%. Now that I'm trying to do that, I realize that I don't know if I should let the computer just shut down on its own due to a dead battery, then charge it to 100%, or if I should shut down the computer myself when I see it's at about 2%, then charge it to 100% with the computer still off (? or is it OK to then turn it on while it's charging?).