Use the overlays as much as you can. The range, movement, and visible hexes overlays are very useful in determining the correct course of action and avoiding accidents.
Preventing lost units
Units can easily get lost in trees and other parts of the terrain because the map palette is not very broad. To counteract this, turn on the unit bases. The game will look less realistic, but you will have a better time keeping track of the infantry platoons.
For better flanking movements, turn on the vehicle facing option.