Most Terradyne and Hoverdyne units in the game have better armor in the front than in the rear. It is equally important to deny the enemy the opportunity to attack your units from the rear or else they will quickly slaughter your units. Attacking from an elevated position is very advantageous. If possible, make sure to position or move your units in shadows. If needed you can even sometimes completely avoid being detected by enemy forces.
Light units can even suppress heavy units.
Use this knowledge wisely and try to suppress an enemy unit if you need to slow down their progress. Even if your units don't inflict any major damage it might give you enough time to regroup. Artillery Vehicles have extremely efficient long-range attacks. However, they are very vulnerable to attacks from enemy units. Make sure to have protective units around your Artillery Vehicles or you will quickly lose them.