I'm not too experienced with them either, but a few suggestions that might help:
- they can hide anywhere; during deployment you can put them somewhere from where they will have a good flanking position later when the enemy engages your frontline
- they have 2 HP; very useful in charges with all the quick-routing going on; might even be useful vs. chariots?
- you can try hiding them and taking out the enemy general... if he doesn't suicide himself first, that is
- since they have few men in a unit, they're not very good as main battle line troops, rather use them in some or other auxillary role