[Endoperez]

Well, one easy tip to give out is to use your starting spells. Not all nations have equally good starting spells, but Abysia can cast powerful Flare, Caelum has Wind Guide (IIRC), which is great help for archers. Machaka has Blindness, good spell but works best when used against few powerful enemies, so isn't really useful on expansion. If your enemy has few strong units without high mr(Black Knigths, Jotunheim's giants, Knights of the Chalice with flaming weapons and berserk), blind them!