Don’t look conspicuous; it draws fire. (For this reason, it is not at all uncommon for aircraft carriers to be known as bomb magnets.)
Never draw fire; it irritates everyone around you.
If you are short of everything but the enemy, you are in the combat zone.
When you have secured the area, make sure the enemy knows it too.
Incoming fire has the right of way.
No combat ready unit has ever passed inspection.
No inspection ready unit has ever passed combat.
If the enemy is within range, so are you.
The only thing more accurate than incoming enemy fire is incoming friendly fire.
Things which must be shipped together as a set, aren’t.
Things that must work together, can’t be carried to the field that way.
Radios will fail as soon as you need fire support.
Corollary: Radar tends to fail at night and in bad weather, and especially during both.
Anything you do can get you killed, including nothing.
Make it too tough for the enemy to get in, and you won’t be able to get out.
Tracers work both ways.