What is Best Practice when storing MacBooks for over a month?

That's what I think Apple suggests when you need to store you MacBook for longer periods:

  • discharge your battery to 50% and keep the laptop in a cool place
  • if you plan to not use the computer for more than 5 months take the battery off the laptop
  • you will probably need to charge the battery every 6 months to better preserve it.

Power it down and make sure it's somewhere where there is no chance of it getting wet.