Task 1: To Zora's Domain
A Few New Items
By the time that it took to complete the Goron Mines dungeon, the Barnes Bomb Shop in Kakariko Village will be back in business. Purchase a bomb bag filled with 30 bombs for 120 rupees. You can now go after pieces of heart #10, #11 and #12. Afterwards, go to the top of the lookout tower and talk to Talo to start an archery practice minigame. Hit as many targets as you can with the bow. If you hit the pole on the top of the lookout tower, you'll get a piece of heart. Later, you can go to Malo Mart to buy the Hawkeye, a handy item that allows you to zoom in on stuff.
Into the Twilight
Once you are done in Kakariko Village, ride Epona north through Kakariko Village. Cross the stone bridge, bombing the boulders in your path. Once on the other side of the bridge, the bridge breaks and shadow beings fall from the sky. Take them out with spin attacks.
Special note: If you don't take out the shadow beings after you use the bombs to take down the boulders, you'll find out far later on that you need that place to teleport the bridge section from Gerudo Desert. Also important to get to the Hidden Village without wasting a huge amount of time going around Hyrule on a horse.
Follow the Scent
Continue onward until you reach the curtain of twilight. Use Midna's help to go through, and get Ilia's scent from her bag. Follow the scent all the way into Castle Town and into Telma's Bar, where Ilia is caring for a Zora child. Listen to her and the nearby soldiers, then exit the town via the east exit.
What Goes Down Must Go Up
Continue east after you exit the town. While crossing the Great Bridge of Hylia, you are ambushed by an enemy that lights the bridge on fire. Climb up onto one of the boxes and use it to jump over the rail.
After you recover from your fall, listen to the Zora soldiers and then listen to Fyer (the clown guy). He'll spot a monster prowling the edge of the lake. When you head after it, it mounts a giant bird and attacks. Dodge its flaming arrows, and jump attack it when it swoops down and repeatedly maul it to do damage. Once you dethrone the rider, destroy it with normal attacks.
Afterwards, Midna mounts the bird and it grabs you. Guide the creature through the cave, avoiding flaming arrows, falling rocks, and the scaffolding. Eventually, you'll reach the base of Zora's Domain and a frozen waterfall. Ascend it by using Midna's help, allowing any shaking icicles to fall before continuing onward.
As you approach the Zora's throne room, you'll encounter three shadow beings. Take out the one protected by the maze first, then destroy the other two at once. Midna will notice that the Zoras are trapped underneath the ice. Warp to Death Mountain, then call Midna when you are near the asteroid that crashed earlier. Warp the rock back to Zora's Domain to melt the ice and start the water flowing again. Ride the current into Lake Hylia, and enter the spirit spring.
Task 2: The 16 Tears
Lake Hylia's Tears
Lanayru gave you the duty of restoring light to its realm by defeating the dark insects that stole it. The first of them awaits right outside of the spring. Follow the wooden bridge to your right and engage your senses to dispose of it.
When you head across the circular island, you'll encounter three more shadow beings. Defeat them and continue onwards to Fyer's shack. You'll find a flying bug near the back of the shack. Defeat it to collect the second tear.
Head south of the round island into a series of small, disconnected islands. Use dash jumps to clear the gaps (head back to the spirit spring if you miss a jump). When you reach the high ground, dig up and destroy the insect.
Now, head to the western edge of Lake Hylia and defeat the fourth bug. After you defeat the 4th bug howl near the fanlike plant to summon the giant bird you rode earlier.
Upper Zora's River's Tears
Activate your senses while riding the bird. When you get close to a flying bug, lock onto it and dash into it while it is not electrified to destroy it and collect its tear. There are four bugs in the cavern. If you miss any of them, fly through again to collect the stragglers.
Listen to Iza's spirit near the boat rental cabin to trigger a bug's appearance. Destroy it to claim your ninth tear, then locate the nearby howling stone. Match its sequence to make the golden wolf appear near the castle.
Tears in Zora's Domain and Castle Town
Follow the path next to the river to re-enter Zora's Domain. You'll find two more bugs in the center of the pool. Stand on a floating leaf to attack them, then head to the western shore. Dig up and defeat the bug there to make your tear collection an even dozen.
Use Midna's help to climb the canyon wall. Partway up, you'll find a ledge leading south (there is a trail of green rupees marking it). Jump the gap to reach the path, and defeat the thirteenth bug. Head into the throne room and run into a wall to knock a bug down. Defeat it to claim its tear, then head back to Zora's River.
Jump into the southeast-flowing river (the one with the torches) for a shortcut to Hyrule Field. Head towards Castle Town, defeating the three shadow beings in your way. A bug waits outside of Telma's Bar. Defeat it to collect the fifteenth tear.
Note: You can take out fifteenth tear the first time you go into Castle Town outside Telma's Bar. You can get it back later as the tear will stay in its spot until you retrieve it. Also in the throne room after you use the rock to melt the ice. So remember those two locations as it will save you the trouble.
The Boss of Bugs
Warp to Lake Hylia, and head to the previously unmarked white dot on your map. When you get there, a giant bug appears. Like its much smaller counterparts, it swoops at you with electrified attacks. Dodge the charges and use your jump attack to hurt the boss. After you damage it, it swims through the water in an attempt to damage you. Stay on land unless you need to dodge an attack and wait for the bug to continue its airborne assault. Once you've hit the boss several times, it falls belly-up in the water. Jump onto it and use Midna's charged button multienemy attack to destroy all six of its appendages at once.
After you collect the spoils from the big bug, Lanayru rewards your efforts by returning you to human form. The light spirit also gives the history of the Twili in the form of an extremely disturbing cutscene. The spirit also tells you that the next item which you seek is located in the Lakebed Temple.