Well, you can always try the 18/18 "Full Six" Build.
Effective as Infantry and Lancer Cavalry at the same time, it's so much fun.
As the name suggests, do 18/18 on 30 and max out your skills:
Here is the build I use for a good start:
Level 30 (4 420 577 xp)
Strength: 18
Agility: 18
Hit points: 63
Skills to attributes: 2
Ironflesh: 5
Power Strike: 6
Shield: 0
Athletics: 6
Riding: 6
Horse Archery: 0
Power Draw: 0
Power Throw: 0
Weapon Master: 6
One Handed: 1
Two Handed: 1
Polearm: 156
Archery: 1
Crossbow: 1
Throwing: 1
(Okay, it'll be full six at lv31, but that +1 IF is insignificant)
You might've noticed that I don't have shield skill. I adapted to it after the slot update, and it worked, just play a bit smarter.
But you can always use the IF points as shield skill, but as a polearm user I prefer more hp when I'm dehorsed, or doing footman work such as piking, or hacking skulls with my Elegant Poleaxe.
Also with 6 Riding, you can ride every horse in the game.