Remember that heavy armor makes you powerful but not
invincible, while the M-1 is superior to the Iraqi's 72's
you can still be taken out by an enemy infantry ambush.
Keep some infantry of your own about to help when the bad
guys try that ambush.
Also remember to utilize your surroundings by using the
terrain and your speed to avoid being an easy mark. For
example if you are using a hilltop to help target your
opponent bear in mind that it's easier for him to target you,
try firing and retreating down behind the hill to help sustain
those longer conflicts by sustaining your life a while longer.
True, it's funny to tear up those Iraqi 72s while their cannon
rounds bounce of your late model M-1s, but don't get cocky and
charge around like a kid on a go-cart course. Infantry ambushes
can still lay those M-1s open like sardines, so try and keep some
infantry of your own around for spotting purposes.
Tanks on defense should use the terrain and mobility to live
longer and make more shots. It might be tempting to sit still
on that hilltop slugging away at BMPs, but you will live longer
if you back down the other side of the hill after your shot.
Your next turn won't be as accurate, but at least you'll
be alive to have one.