A future/modern theme won't need it but I am sure we'll do low tech/fantasy/medieval themes at some point. But, alien planets you visit could have just about any tech level so I guess it could be useful.
Perhaps not, but I could probably extend my knowledge of ancient strategy to modern. It is such a big step, though. Practically only ranged weapons, no melee, and thus the skills of the soldier changes drastically. Endurance is needed more than strength, speed, and agility. Unlike swords and spears, and even arrows, bullets cannot be dodged save through luck. Height plays less of a factor because lasers, as I assume are in the game, do not lose power based on momentum loss, just height. While range increases, power does not.
"In general, hills and defiles gain the importance of cities. Cities the importance of castles. And castles the importance of Heaven," me. But of course, none of that truly matters unless the general himself is a talented one. Being a good general is difficult, because it requires strong rewards and punishments, established after you prove your awesomeness (so the troops look up to you), as well as the ability to judge people perfectly.
War is less about fighting than it is about manipulating personalities. A simple ambush can be pulled off if the enemy general is easily angered. Set up the ambush, send out a bait party of crack troops and have them insult the leader until he attacks, the have them retreat slowly (with skirmishes here and there) to the ambush point. Perhaps the enemy is too timid, then manipulating him can be as simple as banging the war drums every hour or so around his camp during the night. Then after many days of this, he'll get cocky at the ruse; attack when his troops get slack. Have ambushes set up on the easy roads to catch him. Or perhaps the fault lies with you, as general, or that your troops are slack. Then the best place to fight is with your back to the river, surrounded on all sides. Each soldier will fight harder than ever, and if you guide them through the weakest point of the enemy army, you will survive. "If a soldier fights to live, he will die. If a soldier fights to die, he will live."
There are, of course, thousands of basic pointers, but it all begins with a good general. He must inspire the troops, the troops must think of him as a father, easy supply train, good weapons and armor, constant training in formations (formations themelves are more important than the quality of the weapons, not to mention) as well as combat, squads made in teams of 5, and the like all make a good general.
The most basics of the basics, which are almost NEVER implemented in strategy games, are these: fight with the sun to your back; fight small skirmishes with less troops against larger numbers; unorthodox and orthodox troops, and some others. Obviously, if the enemy can barely see you, the advantage is yours. If you're on a hill, the extra momentum is deadly (this is usually implemented, though). Small skirmishes whittle down larger numbers (think guerilla). Orthodox troops are those who fight "by the books" and charge the enemy from the front. Unorthodox are the special units in tactics, such as those who flank, burn out the supplies, burn the enemy flag from the top of their castle and fly yours, those who tunnel underground, and tactics like that. Being able to assign a unit to be "orthodox" should grant them front v. front advantages. The drums in ancient war determined marching speed. Two strides for every beat was common. However, unorthodox troops would have different orders for them. One stride forward, then two strides to the left, or triple pace, or on the roll, they drop their weapons and flee.
...sorry for rambling. Anyway, ::disappears::