General strategy[edit]
Depleting the enemy's fame points is usually the most important priority at the start of each mission. M-48s and factories can play a useful role in this, by destroying enemy aircraft.
The flag tank can be pretty useful (kinda like a king in chess) if you advance it into the center of the battlefield to dominate that area with the help of some other units. Don't do this if there are enemy bombers, Mi-28 Havocs, or the enemy flag tank close by, though, or they'll take the opportunity to attack.
Infantry, commandos, and the flag tank are pretty effective at weakening an enemy Mi-24 (without losing too much fame in the process) to the point that you can finish it off with your own AH-1S Cobra. The flag tank can usually lure in an Mi-24 to attack, but the Mi-24 usually won't be able to inflict enough damage to destroy it on its own. It'll just use up a lot of its missiles and take some damage from your cannon.
Often, winning missions (e.g. mission 4, Cats & Dogs; mission 6, Crossing the Barrier; mission 16, The Final Conflict) comes down to avoiding the enemy's main force, and taking your main force down an alternate route to attack his flag tank, which has usually been left by itself back near his factories. When you're trying this strategy, don't bother taking cities or resupplying unless you have to; just go full speed ahead down the alternate path toward his flag tank.
In some missions (specifically, mission 10, The Link of Destruction), you start with a bomber and can just go on a blitzkrieg attack to demolish his aircraft factory before he has a chance to produce any aircraft. You'll probably lose your bomber, but it'll be worth it to put his aircraft construction abilities out of action, so that you don't need to worry about building any M-247s, M-48s, or fighters.