Stances and Clumping
D = Aggressive - Generally, use this stance when you are attacking things that don't attack back (e.g. buildings).
F = Battle (Default) - For the most part, avoid this stance.
G = Hold Ground - Your units should usually be in this stance unless they are attacking a building.
The best advice for any player, when you want to attack a building, select the battalion. Make them run around the building corners, then make them attack the building. By running around the building you make your units clump together, so when you attack almost all of you battalion is attacking the structure, instead of only the front units.