Use a 0-100 map grid for Fables positions. X runs west to east (0 is west, 100 is east). Y runs south to north (0 is south, 100 is north). These are rough placements to match Avatar geography, not surveyor's points. When a character moves, update the POI, not just the grid.
FIRE NATION AND NEAR WATERS
The Fire Nation island cluster sits in the west, roughly x 5-28, y 32-68. The Capital, Hari Bulkan in the Caldera, is about 16, 50. Crescent Island Fire Temple is about 22, 48, a short sea hop. Ember Island is about 14, 58, a pleasure island north of the Capital. Hira'a is about 18, 42, a quiet town south of the Caldera, later a hiding place. Lambak Island is about 10, 44, off the western fire coast. The Fire & Air Center of Learning is about 20, 54. Yuyan Forest, the Forest of Whispering Needles, is about 19, 56. Ashfern Hermitage is about 12, 48, in the western hills. Shu Jing is about 21, 44. The Sun Warrior ancient city hides about 11, 38, in rough volcanic country, and should not appear on official maps the party is handed. Roku's Island sits on the eastern edge of Fire waters, about 24, 52, still smoking.
The Mo Ce Sea, the water between Fire colonies and the western Earth Kingdom, is roughly x 24-36, y 30-70. Yu Dao stands on the Earth shore of that relationship, about 32, 52.
EARTH KINGDOM
The Earth Kingdom dominates the mid and eastern map, roughly x 30-95, y 22-78. Ba Sing Se, the great walled capital in the northeast of the kingdom, is about 82, 66. Lake Laogai is just beside it, about 80, 64. Omashu is about 44, 42, a mountain city closer to the west-center. Chenbao and the Northern Passage are about 58, 76, a cold coastal flashpoint toward the north. Kyoshi Island is off the southeastern Earth coast, about 78, 20. Foggy Swamp is about 50, 28, an interior wetland. The Si Wong Desert and the buried library sit about 62, 46. Senlin Village is about 70, 58. Hualin flood ruins about 50, 26. Gaoling foothills about 68, 36. Broken Cliff Academy can sit in rugged earth near Sud's traditional range, about 60, 40, unless you prefer to attach it to a named mountain closer to a party home.
THE POLES AND AIR
The Northern Water Tribe and Agna Qel'a occupy the high north, about 50, 94, in a box roughly y 82-100. The Southern Water Tribe and Wolf Cove occupy the far south, about 48, 8, in a box roughly y 0-16. The Sacred Island between the tribes can be placed in southern-temperate waters, about 46, 16, used as a conclave site rather than a polar capital.
Air Temples: Southern about 36, 18 (near southern earth and airy islands). Northern about 64, 80 (mountains toward the north). Eastern about 90, 44 (far eastern ranges, mine-scar nearby). Western about 28, 46 (inverted cliffs facing Fire waters). The Guiding Wind Unbound Circle camp currently sits in mountains above the Fire & Air Center, about 20, 55.
SPIRIT GEOGRAPHY
The Spirit World does not need a single grid square, but for a pin use a place off the mortal map or overlay Roku's Island echo at 24, 52, Koh's lair as a deep-sea spiritual mark, and Forgetful Valley as a distant optional pin in earth forests, about 74, 50, only if a quest goes that far. Wan Shi Tong's Library is physically in the Si Wong at 62, 46 even when it feels like another world.
TRAVEL
Ferries and official barges stitch the Fire Islands. Coal fleet ships work the Mo Ce and the outer coasts. Earth travel is caravan, ostrich-horse, earthbending rails of convenience, and long walks between rings and states. Water Tribe cutters work the poles and the Passage. Sky bison make temple-to-temple travel possible and rare for outsiders. Official barges already turn back civilian boats that ask too many questions about the eruption. Bison will attract "census" interest from the wrong eyes.