I usually roll into battle with about 60 elite rangers, 40 ivory archers, 40 champions, 20 einharjars, and 40 sergeants ( they usually have large shields), and about 40 cavaliers. Against enemies, other than khergits or dark knights, I rarely even use my cavalry. I just find a hill, set up the archers, set up the line of infantry in front and f8 a few times to both the archers and the infantry to make them stand closer. The AI usually tries to flank slightly with their cav wedge so I readjust infantry line accordingly as my archers and myself are sniping the hell out of them. I usually try and shoot the lead guy in the wedge (usually the lord but not always) because their formation breaks and they retreat for a second and reform. Even if their cav makes it to my line of infantry and gets a good charge in I rarely have any casualties. I don't know if its because sergeants sometimes carry braceable weapons or what but usually only 2 or 3 horses make it through their line alive. If i'm getting bored with this tactic I usually have my cav follow me and sweep in a wide arc around the enemy so as soon as their archers start to stop and shoot and get separated from the rest of their force I ride them down from behind.