You must make your way through the Royal Crypt to unlock the path to the next element.
Explore the Crypt
This is a mini-dungeon. To defeat mummies, burn their wrappings with your lantern and they turn into stalfos. Be careful, the mummy can grab you and drain your life. One of them holds a small key, so beat the monster and get it. Then move on to the next room.
Pull down the leftmost mushroom to get to the other side. Don't touch the left or right door, they're fake and will hurt you. Unlock the middle door and go through.
You need two keys to progress, and you get them both in this room. First go to the right and down. There's a trap moving around the edge of a long line of blocks. You need to use the glowing tiles to split into three, careful not to let the trap hit you (or hit your sword) while you split. Charge up your sword and let the trap pass before stepping on any tiles. Then when you've split, maneuver around the blocks and avoid the trap to get up to the top (let the trap pass before trying to keep going up), and step on the three switches to make the first key appear.
Now go over to the bottom left of the room. Charge up your sword and step on one of the tiles, but wait until the moving platform comes near before splitting into three, timing it right so you can step on it right after you split. Ride the platform and again maneuver around the blocks to get safely to the top, step on the switches and get the second key. Go back to the center of the room and use the two keys to get up to the next area.
Defeat the ropes that charge at you, and continue to the next room. Light the four lanterns to make two mummies appear. The torches will shoot fireballs at you. Carefully defeat the mummies as before, then go through the final door.
Step up onto the platform to get a special gold Kinstone piece. You'll be taken out of the crypt.
Now a bunch of Kinstone fusions have opened up. Fuse twice with the ghost hanging around the graveyard (you may have to go indoors then out again to get him to do the second fusion, just go down the steps that were under the tombstone at the top left).
Fuse twice with Dampé.
Go down the steps that were revealed with one of Dampé's fusions, grab the chest for 100 mysterious shells, and fuse twice with the girl ghost in here.
If you talk to Dampé, he'll tell you a special path through the Lost Woods, with the final direction missing. The correct path is left, left, left, up, up, up, up. So go into the Lost Woods and follow that path, and before the last "up" you reach a chest containing 200 mysterious shells. Go up once more to reach the graveyard again. From there, warp to Hyrule Town.
While here, go into the path through the waterfall that the girl ghost opened for 200 mysterious shells.
Also, shrink at the library and climb down the ladder, then swim into the stream. There is an arch here to swim into. If you go up then west, you reach a frozen chest. Thaw it out to get 100 mysterious shells. Go back out and grow at the library again.
Fuse with Din, Nayru, and Farore. The butterflies that appear around the world will increase your skills.
You can now go down the ladder next to Mayor Hagen's house and split into three, and push the block up to reach a rock you can push into the last hole. Now that all three rocks are in all three holes, you can pull down the totem pole into the large area and push it out of the way. Then pull the pillar with the chest on it straight down, and push it into the hole there to be able to open it for 200 rupees. Then, above, bomb the blocks out of the way to reach a chest with 100 rupees in it. You don't need to bomb the rest of the blocks, they just lead to a path that takes you into the school where Potho's statue is. If you go into the school you can push the statue to one side to reveal stairs leading down to that area, but there's not much point.
For now, go south to South Hyrule Field. Use the warp tile thing above Link's house. Fuse twice with the woman blocking the doorway. Then fuse with the woman by Gregal's bed. Now warp back to South Hyrule Field.
Shrink down at the portal to the southwest, then jump in the water. Up north is a small arch you can get into for a piece of heart.
There should be a ton of fusion treasures around the world right now, particularly in Castor Wilds, so go around and get them if you wish. Just check your map for locations.
In the Trilby Highlands, go north from the Hyrule Town exit and get into the water. Use the mole mitts to dig into the cave. The chest here contains a red Kinstone piece. Head down the ladder to reach a fountain with fairies floating about.
In the Western Wood, you can go down to Percy's house, light the torches inside, and reveal a monster (it won't attack). Talk to it to get 50 rupees. Then go back out and in to find Percy back in his house finally. Talk to him to get 100 mysterious shells. Around the Western Wood are a bunch of paths opened. Some trees are up, giving access to spots of dirt that you can dig for rupees a piece, side by side. One tree is up leading to a chest that contains 100 mysterious shells.
In Castor Wilds, collect the joy butterfly to boost your digging speed. Go up to the golden rope and beat it for 100 rupees. Then go to the northwest corner over the swamp and shrink down. Take the lilypad south and into the crack. The chest here contains a red Kinstone piece.
Now take the log south, and continue to head east. South, in the swamp, is another lilypad, which takes you to a piece of land with a vine going up that takes you to a crack. The chest inside holds a red Kinstone piece.
Ride the lilypad back to land, go up and east through a log, and continue to the southeast area of the Wilds. Get in the water here, and there is a small arch into which you can swim. Go up the leftmost path to reach a chest containing a red Kinstone piece. Then go up the second to the right path to go through the door here. Beat the monsters with the blue mandibles, then push the leftmost block up, the one two blocks over up, and the middle one to the side. Beat the monsters through here. At the top, the middle three blocks are the ones you can push. Push the left of the middle up, the right of the middle up, and the middle one left to reach the piece of heart. Now you can go back outside.
Go all the way back to the lilypad at the northwest of the Wilds. Ride up and go through the log to the Minish path above. Gust your way up, then go into the left-hand crack (you already went into the top one for the bow). In the chest is a red Kinstone piece. Then go back out the Minish path and to the final lilypad to reach a crack in the corner. The chest contains a blue Kinstone piece. Go back and grow. Then use the ocarina to get to the Wind Crest here in Castor Wilds for quicker access to the Wind Ruins.
Get the Joy Butterfly that's here. There may be various treasures around here. To get into the crack that may have appeared, you have to go all the way to the second portal and shrink. Backtrack, going down tiny vines to get from screen to screen. There will be a crack in the ground on the way, go in it to get a red Kinstone piece. Then go back out and down the middle vine to reach a tiny opening. Make your way through this simple cave to get a piece of heart. Then go back out and continue to the second shrinking portal to grow again.
There may also be a chest near where you entered the Fortress of Winds, it contains a big bomb bag.
Once you're done, warp to Hyrule Town, then west to Trilby Highlands. From here go to Mt. Crenel Base.
First make your way to the Crenel Hot Spring via the Minish path. In there is a chest containing a blue Kinstone piece. Go back out and grow, then warp to the Mt. Crenel Wind Crest to get near Melari's Mines. Shrink and go through the mines to the Minish path up north. In the path is a chest containing 200 mysterious shells. If you want to fight it, there's a golden tektite a little lower down. To make life easier, exit right out of the Minish path rather than going back through Melari's Mines. Grow and use the ocarina to get to the Mt. Crenel Wind Crest. Now drop down the ledge to the bottom left and continue down to the golden tektite, and beat it for 100 rupees. Otherwise use the ocarina to get to Hyrule Town, and exit to North Hyrule Field. Go north past the four trees, then take the northeast exit to Veil Falls to find the source of the flow.