My favorite tactic, generally speaking, is to have a front line of lighter infantry to absorb the initial impact and tie-up the enemy battle line with a unit of spears or pikes at the ends to help protect against enemy cavalry circumventing my lines.
I place my heavier infantry in the next rank so they can be moved-in as needed to reinforce the front line or take advantage of holes in the enemy line. I tend to put the best troops of line two on the wings; if you can start to roll the enemy up like a carpet it's all over for him.
My missile troops make up my third line with skirmish mode off (only turn it on if my line becomes compromised) and in guard mode so they can decimate reinforcements and cavalry.
My own cavalry gets divided into two groups on either wing, ideally comprised of heavy and light horses on each side. The light horses can deal with enemy skirmishers and be sent after missile troops once the enemy's main forces are engaged. My heavy cavalry waits until they are needed to help smash the enemy's wings from behind or attack targets of opportunity like generals. Having them behind the enemy line when they break is also helpful in maximizing casualties when my foe routs. If they don't survive they can't attack you again...
Spr LInf LInf LInf LInf LInf Spr
LCav HInf HInf HInf HInf LCav
HCav M M M M Hcav
General