I use archers in defense, and in attack when the enemy is lacking missiles. Otherwise, I can't be bothered dealing with missile duels, they are just too wasteful and I'm just not good enough to micro mine effectively. It's so much easier to just rush the lines and send cavalry around to crush or disrupt the enemy's weak archer units. This also puts the cav is a good position to charge the rears of anything that withstands the main assault. Each enemy archer unit is just one less infantry block to deal with. I will use archers against javelin units though, they are just too nasty (but fortunately short ranged) to leave alone.

If attacking an enemy that lacks missiles, then I try to let my archers expend all their ammo before starting the melee. Not only will this save my infantry and cav, but it also valors up my archers for better accuracy later on. High valor missile troops can be handy when 1230 rolls around.