The majority of the Miracles in the game can be acquired from Irina of Carim, a prisoner you will need to free in the Undead Settlement. To do so, go out from the Undead Settlement, Dilapidated Bridge bonfire heading towards the Curse-rotted Greatwood boss fight. Before you go through the building after the Giant is throwing arrows, take a left up through the graveyard and go pas the hut where the Thrall drops down on you to find the Mortician’s Ashes. Take these back to the Shrine Maiden in Firelink Shrine to be able to buy the Grave Key for 1,500 souls
Assuming you have opened the shortcut next to the Dilapidated Bridge bonfire (go up and around from the Cliff Underside bonfire then right through the gate into the sewer, at the end, climb the ladder and open the gate) head down into the sewer pass the Giant Rat and use the Grave Key on the gate to your right
Careful down here as the skeletons can mob you, make your way through and outside, head up the path in the gulley. Take a left, into the room full of Rats, climb the ladder to find Irina of Carim, agree to Touch Her then accept her service where she will then go to Firelink Shrine, to find her, go off to the passageway on the right of Andre the blacksmith