Help with Sif anyone?

Hello all. I'm trying to kill Sif to get the Artorias ring so that I can go fight the Four Kings to join the Darkwraiths. I'm soul level 36. Would anyone be willing to help me kill him, and then possibly help me speed-run through New Londo to help with Four Kings afterwards? If you don't want to do New Londo with me that's fine, I can figure it out later. I would really appreciate if someone could help me with Sif though. Thanks in advance.