See, the big problem with Advance Wars is they want you to play the same way the AI does but with a bunch of things switched around (i.e. the AI can see through FoW but won't go near forest tiles if they know you're there while at the same time you don't need to go through a build order etc.) when really you should just learn two playstyles, one for dealing with the AI (which has GLARING exploits, some stated by the game itself, like throwing APCs as bait, and others that you'll find out by trial and error, such as the building patterns they AI has to go through so that you know which enemy to prioritize so that the limitless funds of the AI only produce innocuous Infantry or the likes) and another entirely different for dealing with human players.
Usually the best strat is to have a main platoon as a distraction to the enemy and to just move around the forest tiles with ground transports and loading and unloading infantries as you see fit, then storming their HQ. Works on most maps without even having to do that faggy reset strategy people use to manipulate the RNG. I say this because the enemy literally cannot stop sucking dicks when it comes to transports, also their air units try to move the maximum distance they can and do not understand the concept of resupplying.
Told ya mate, multi and single player campaign are completely different experiences, maybe you really need to get some of that multi experience. Alternatively, you can try and play AW Days of Ruin for the DS, since the AI of that game is actually bound to the rules of the game, tends to make much less retarded decisions and the COs aren't nearly as useful as in the original trilogy.
If you really wanna stick with the original ones though, let me give another couple of hints:
- Like I said previously, the AI in this game is kind of bonkers when it comes to their build orders. Usually they follow a strict checklist of which units they need (you can see that on maps like Spann Islands where you get similar results each time), the key factors are the COs deployed, how near your units are to their HQ and what kind of unit is nearest to one of their bases. You can feed it false information by killing specific units and/or sending units you want to be countered against by them (i.e. sending a copter within an air base will usually result in them building an AA, even if you have some tanks nearby that can easily fuck it up, similarly you can bait it into building an unit in a faraway base while their HQ lies undefended). The game tries to force you to do the same but most of the time you really don't, just learn the map layout instead, as it provides much more useful information.
- The game makes a huge deal about you having to conserve your units (lest you want a lower Technique level) and bases… But you really needn't. The only thing that matters in most maps is the enemy HQ. Routing only seems easier because the AI goes on suicidal attacks if they can get at least one of your units, but you'll soon see that routing is usually harder, longer and less fun than storming their primary defenses. It's okay to bait the AI into capturing your own cities or taking bases and airports, because, again, the AI only builds a set amount of certain units, so one Infantry capturing your building is still one Infantry less guarding the HQ or capturing a base closer to their own HQ. Don't force yourself to play too conservatively either, bait the opponent with a unit and get four more kills to your death toll. In a map like the one you just posted, the light tank is pretty much useless, so it's okay to put it somewhere the enemy will desperately try to reach it and counter with all your anti aerial devices.
- Try to spend in just the right amounts and only when the time is right. Again, the game and the AI make you feel pressured into keep building each turn to get your unit count to match the enemy and have these huge skirmishes that ultimately play like a WWI reenactment, but you really do not need to buy units all the time. Just pick something that gets you to the key chokes and buildings faster than the enemy can. Usually 4-ish Infantries are more than enough to capture all you need in the map. In multiplayer however, spamming is not only rewarded, it's basically a requirement to match the enemy, since they're not dumbasses with cheat codes and hence know that on capture-limit maps it all boils down to who gets the most territory colored the fastest.
I think it's just cause Max is insanely overpowered in the first game and Sami's COP hardly matters in this game anyway.