Advance Wars: Days of Ruin - DS/Quick Strategies

From WikiCheats

Terrain

Learn to use the terrain, especially in those tricky Fog of war battles, getting an infantry onto a mountain vastly increases your area of sight and allows you to bring in those long ange units like the rockets.

Units

There are alot of different units in the game and so you need to learn how to use them well, Remember to keep your spendings to a low in battle so that you still have enough for some better units when you need them.