I think one of the biggest mistakes I see is not being agressive enough at the start. Almost all maps have an equal amount of zones for either side plus one contested zone. The furthest zones of "your" side are the ones you want to push into from the start at all cost. It's a big gamble trying to take enemy zones right off the bat but if it works out you've pretty much won the game.
The "contested zone" is a different issue. You can try sending a token force to get a foothold and reinforce it later or commit most of your force to prevent the enemy from gaining a foothold.
A lot of these options depend on your deck design. Motorized transports are an obvious choice for early aggressive pushes. Helicopters arguably less so because of their price. It can work out but if you loose, you'll loose a lot of points for delaying the enemy a bit. However, airborn really starts to shine on the largest maps, otherwise a single card of helicopter infantry is enough for quick reinforcements and fire support.
Aggression during the game is an entirely different matter and depends on the situation. You want to make sure to sustain the push with a constant stream of reinforcements. Try to anticipate what units you loose and call them in before you loose them. Combined arms is king obviously. On the flipside this means that destroying certain elements of an enemys defense can open opportunities. If the enemy super-heavy tanks are too much to deal with, try disabling and/or overwhelming the AA net and sending in ATGM planes and helicopters.
Wargame does have a few 'hard' counters (e.g. ATGM helicopter vs tanks) but most of the time you're looking at soft counters. Smaller tanks get wrecked by heavier tanks but add a single 20pt Afghanski or mortars to stun the heavy and the situation changes dramatically. Likewise if you're able to flank the enemy. Moral plays a big role in Wargame and any panicked or stunned unit is essentially worthless.
Fire support plays a key role, especially in forests. Event the 5pt transports can serve as a force multiplier. Just keep in mind to engage with the infantry first, as then the enemy's MGs will focus on the squad and they wont fire their AT on vehicles unless ordered to. And if your fire support isn't a crappy 5pt transport but an afghanski or a base line T72 you'll cut right through the enemy.
The shiniest units aren't all around killing machines, they only excel in their respective field. An Apache Longbow is still going to die to a manpad team... And the most expensive tanks can be suicided by an ATGM plane (which will still cost less than the tank). Cheap units, especially infantry, are important to draw fire, overwhelm the enemy (even a crappy gun still stuns things) and to keep up momentum. A steady stream of line infantry keeps the enemy occupied while your panicked and wounded commandos can fall back and get resupplied.
Speaking of which: Logistics is important. No matter how trashed a unit is, they can be nurtured back to full strength. Reverse wounded tanks (there's a hotkey for that, bind it somewhere in reach) to keep the front armor towards the enemy, use mortars to help your infantry fall back etc.
That's about all I can think of for now, hope that helps.
Edit: Also you need to get rid of the F-14 GeEom.
Games that are not ArmA2 or Flight Sims