Firstly, Advance Wars is amazing (only on mission 16 thus far).
My strategy for mission 8, and I'm pretty sure I got an S for it since I've only managed one A thus far, was to crank out infantry first thing and get them on the buildings nearby and to the right (whie avoiding the piperunner). Soon as you start making money start building tanks, while you keep taking over cities. Take out the pipe runner and either take over that base right next to it or sit something down there to kill the one black hole infantry that will try to take it over. You wanna basically concentrate your effeorts on the right side, putting some tanks by the bridge, but not past it, so that you're always only fighting one enemy at a time, and a few tanks with the infantry you sent down the far east (where there's an airport). Once the air port is yours make a bomber and from there it's pretty easy to wreak havoc on the enemy. I don't remember if you have Colin by that point but he's a good to CO to use because of his cheap production costs, and you won't actually be fighting a whole lot at once, I don't think. Anyways, that was my strategy as I recall for that mission (assuming that is mission 8).
