Due to the troubles of getting a lot of people playing at the same time (Mostly because this community is still very small and from many time zones) a forum thread discussing strategy might be better.
One useful strategy I use is a box. Spears and glaves do a good job slowing down attackers. Samurai can usually get in there and finish the attackers off. This is used to defend against cavalry rushes.
After reading The Book of Five Rings I often think about positioning. I try to move my ranged troops as a unit, They start inside the box (low position), then sprint into attack range (high position). When the enemy responds I either move the ranged units back to the box, or advance the box and turn it into a line (middle position).
There are a couple other attacks from the book of fire I have tried, but that kind of philosophical stuff is hard to relate to specific tactics in the game.