Some tips for keeping cables secure may prevent cracking because the ports are attached to the case, and are easily damaged if you don't remove cables properly*
http://www.macmaps.com/frayguide.html
Also only use the machine with dry hands. Do not allow food or drink near them.
Shut down machine before transit anywhere, unless you are going to use it immediately a lot.
The heat buildup in a bag can damage the machine if the display accidentally turns on while the display lid is closed.
Pay attention to the spec heat limitations of the machine on the outside
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