Farmed the knights for like an hour and didn't get one humanity drop. I went to the white ninja room and gods be praised, found one, but I fucking died against those stupid demons in that small ass room trying to get back up. I died again trying to regain it.
I don't know why they would just dead end players like this. The boss fight is impossible with my gear and set up, I get slaughtered and trapped in a corner as my camera spazzes out due to the lock on, and the game flips a coin between running and rolling. They couldn't have put a humanity merchant or a damn rat anywhere near the boss? It just sucks that I managed to get this far but then some crummy things happened and now I can't progress. Throw me a damn bone here From.
If you need humanity and you don't want to farm enemies that drop it, simply drop down your own summon sign - for every person you help defeat the boss in co-op you get souls and a humanity. You can also buy some from some of the merchants.
Co-oping is really the best way since you will also be getting experience of fighting the boss if you are having trouble.
Remember with O&S only concentrate on one of them - you can never kill both of them before the cutscene and one of them supersizes - decide who's armour you prefer because that will be the one you can purchase, so kill them second. People say Smough is easier, I've never had a problem killing Ornstein second and it's my preference to do so.
When you see either of them going for the butt smash, roll back, back back. And get your armour down to 25% equip. load so you can fast roll. Carry a 100% block, high stability shield. If you want to still wear decent armour, use the DWGR or Havel's ring.
I think I'm right in saying they are weak against fire - so pyro and fire/chaos weapons.
It can be frustrating to summon in Anor Londo because it's such a high traffic area for invading, but there should always be plenty of summon signs down in the bonfire room, so summon a couple of helpers then run to the boss fog, dodge the giant guards, no need to deal with them.