Obnoxiously requires you to be at least on NG+ and advance three different covenants with 10 of their respective items each.
10 Eyes of Death for the Gravelord Servants, which can be farmed from Basilisks and have to be handed in to Nito before killing him on that cycle.
10 Souvenirs of Reprisal for the Darkmoon, which can be farmed from the crow enemies in the Painted World and must be handed in to Gywndolin before killing him on that cycle.
Then most obnoxiously of all, 10 Sunlight Medals for the Warriors of Sunlight, which can be farmed from the Chaos Bugs in Lost Izalith (the enemies that drop the Sunlight Maggot). The Warriors of Sunlight themselves have a Faith requirement of 25 to even join, decreasing by 5 for every boss you help defeat as a white phantom. You also need to exchange Gywn's soul on NG+ here for the Sunlight Spear.
A cheeky miracle missable until the next NG cycle is speaking to Siegmeyer at Firelink Shrine, after helping him in Anor Londo.
The rest can be hunted down before finishing your NG cycle at any time, unless you do something silly like kill Reah or Oswald.