If possible, have at least a few cadet soldiers guarding fringe installations they're not a huge investment, and during the heat of battle they'll provide a last-ditch defense against virusing, which you don’t want.

When preparing a Darken siege, remember to select Passive Cloak for invisible units; otherwise, they may attack a passing enemy and expose themselves prematurely.

Remember to defend your umbilicals! Nothing’s so galling as having your entire strategy subverted by a wandering enemy force that lucks upon a critical link in the power chain and destroys it.