i find it nearly impossibbile to carry out coherent plans in those environments as I often have no idea what any of my own or the enemy forces are doing or even where they've got to when they've moved from their original positions
I love forest battles for precisely those reasons :)

Even better with minimal UI. Light cavalry to go find the enemy, march your army up close then just charge whatever you can see. Great fun. Or even better; in RTR i pretty much covered the entirety of germania with trees and sat and waited for big stacks of macedonian phalanxes to come get my little armies of under-dressed germans. So cool.