As far as other strategies, a favorite one of mine is to keep a large reserve. This gives the player a great deal of flexibility as well as the ability to quickly "hide" the cards in a position that has been revealed. This is simple to accomplish during the movement phase by pulling revealed cards back into the reserve and replacing them with fresh "unrevealed" cards.
Another little stratagem is to let one of your "higher" cards get hit, especially if you have a general and/or modifier that means it will only rout on a six. This does seem rather counter-intuitive. But these cards have a much higher "save" percentage. Thus all things being equal, by doing this in certain situations, you will end up with the same number of attack factors, they will just be spread out through more cards. Some of the games that my wife and I have played have come down to the opponent not having enough cards to man all the positions. This being the case, the player with artillery of 1 and 2, and infantry of 2, 1, and 1 (five units totalling 7 CV) is in a much better position than the player with a 3 artillery and a 4 infantry (2 units totalling 7 CV).
USE your generals! They do you absolutely no good in the reserve. If you are making an attack and only have "defensive" generals, it still might be a good idea to stick one with the attack. At the very minimum, he can absorb one hit that would otherwise hit one of your units.
Stick those good defensive generals in a position that is taking a lot of artillery fire. I had a position in one game that was getting 5 artillery rolls against it per turn. I kept a 3 infantry and a 3 cavalry in the position as well as a 1/2 general. The cavalry must have taken 10 hits before it finally rolled a 6 and routed. This is where using a high CV card to absorb hits can really pay off, especially if you are in a defensive situation.
When to Attack and How
Other Strategies (this page)
Breakdown of "Special" Cards
Strategies for Each Side