This page covers smaller tips for Red Alert, and handy hints as well. Basically things that don't belong in the other sections of the Guide.
Computer allies are useless
As the heading says, computer allies are useless. Upon allying with an AI they will crush your men, send lots of units pell-mell into your base, and most importantly, will not help against the other AI players.
In this game I allied with the yellows to see if they would help me against all the other teams attacking my base. As you can see, the brick reds, lime greens, blues and oranges are all attacking my base (my Construction Yard in fact) and the yellows are doing absolutely nothing to help. If they helped protect you, and co-ordinated with your units in attacking, allying might have a use, but it doesn't and is utterly pointless. When they crush your men it infuriates you, but at least you can force fire the offending unit(s) into oblivion.
Retargeting selling buildings
When you move in for the kill on an enemy base, you'll notice they often sell structures once you get them down near and in the 'red zone' of health. If they do sell it, it denies you a kill and gets them money and also takes away some of the satisfaction. Also, more men appear from the sold structure than if it was destroyed, adding extra infantry to the fight you hadn't bargained for. As soon as the computer sells a building your units automatically disengage from it, but be on your toes and immediately re-apply the target. The chances are you'll be able to destroy it as it deconstructs, thus getting you a kill, denying them cash. The five or so men sometimes still appear, but look at that as a way of getting even more kills.
If your tanks have to manage without anti-infantry support, then you'll just have to move your units over enemy infantry when you encounter it. The AI likes its men, and will throw a lot at you. Infantry, when used properly, can play havoc with armour, and the enemy often avoids your scatter commands by using its own, so simply target ahead of the infantry and have your tanks drive all the way through the enemy. Even if you don't crush them all, their weapons won't be as effective against your moving tanks.
As you are probably aware, units travel much faster on roads. A Light Tank, APC, Ranger or whatever, travelling on a road moves considerably quicker, and this is useful to know if you are making a hasty retreat (or "tactical withdrawal" as I like to call them).
A very simple method to get more cash quickly, as early on in games you'll need it. It's better to have a steady stream of ore coming in once you're established but initially make sure your trucks go for the gems. And make sure you keep an eye on your trucks. If you target one to a far ore field it may get there and stop. This might be because you accidentally targeted some grass, or you targeted some ore that another ore truck has harvested since, and the new truck now has no target so will stop dead. Keep an eye on your trucks at all times, and keep them up to strength. Also, keep building. "Silos needed" is not only annoying, but bad because you're losing money!