How to efficiently group units on the battlefield?

[Spartiate]

Hi Duke.

I tend to group heavy infantry in one line(my main line) in the center of my formation.I group light infantry/skirmishers slightly behind the front line and flanking it.I group archers and place them in a line behind the heavies and not too close to them and i normally have two groups of cavalry out on either flank but starting well behind the main line as i don't want the enemy to turn towards my flank too early.
This is my most common basic line up when using Infantry based armies with good heavy infantry.It varies when i use Barbarian Factions or HA Factions.
I have found that you can then group your GROUPS together and on the unit panel the original groups you created are still adjacent to each other making it easy to separate them again when you need/want to.The advantage of creating one huge group from your smaller groups is that it is so much easier to move them before the battle is joined while keeping the defensive formation you want e.g heavies protecting archers,skirmishers protecting heavies flanks,cavalry protecting skirmishers and archers creating a killing ground around your troops in effect protecting them all.