Here is a list of the heart pieces I have found . Will add more when I find them!
(A) means that you can only get this piece when Link is an adult, and (C) means you must get it as a child.
Play your ocarina with the two flute boys in the Lost Woods 4 times to get a piece of heart. (C)
In Gerudo Valley, there is a wooden box on a ledge. Drop down to the ledge with the grey boulder on it, and hookshot to the crate. Smash it open for a piece of heart. (A)
Go to the far end of the field at Lon Lon Ranch and go into the building. Pull the crate in the top right back towards the door, then pull the crate in the top left corner to where the other one was, and crawl through the hole. (C)
Plant a magic bean at Zora's River, and ride it around....you will see a piece of heart on a pillar...jump off and grab it. I have heard you can get this with a chicken...will try it.(A)
At Zora's River , when you get the hover boots, you can get the heart piece on the ledge by the waterfall. You can get this with a chicken also.
Play the 'Song of Storms' for the frogs in Zora's River. (C)
In Kakariko, either get the owl to fly you to the roof of the chicken lady's house, or hookshot there, drop down onto a ledge on the side where her chicken pen is, and go through the crack in the wall.
Hookshot or ride the magic bean in the Kakariko Graveyard and smash open the crate. (A)
After getting the hookshot, when you come out in the windmill, jump onto the rotating boards and grab the heart piece.
(A)
Hookshot to the guy sitting on his roof in Kakariko. (A)
When you get the iron boots, use them to sink to the bottom of Zora's Lake for a piece of heart. (A)
Snag 1,000 points in the archery game at the Gerudo Fortress. (A)
In Death Mountain Crater, climb down the ledge facing the Triforce symbol.
Use the magic bean next to the Desert Colossus, and ride it...you'll see the heart piece. (A)
Swim up behind the big waterfall in Gerudo valley, and climb the ladder for...you guessed it...heart piece!
Plant a magic bean next to the entrance to Dodongo Cave, and ride it. (A)
Use a bomb in the middle of the fenced in area right before Lake Hylia.
Win the treasure chest game in the Market , and use the Lens of Truth to cheat. (C)
Defeat 50 skulltulas, and your prize will be a heart piece.
Defrost the heart piece in the compass room of the Ice Cavern. (A)
Use a magic bean near the scientist's hut by Lake Hylia, and use it to jump onto the roof. Climb the ladder to claim your heart. (A)
Light all the torches in Zora's Domain (use Din's Fire to light the two behind the waterfall, then light a Deku Stick and light the others). (C)
Return the lady's dog (she lives in the alley in the Market) at night (it's a white dog, usually playing by the Item Shop) and she will give you a piece of heart. (C)
Play the 'Bolero of Fire' as a child, and plant a magic bean next to the Triforce symbol. Come back as an adult and ride it to the top of the rock to get the heart piece. (A)
Catch the big fish (lunker) in the fishing pond as a kid for a heart piece. (C)
Play 'Saria's Song' for the Skull Kid in the Lost Woods (one screen left from entrance). (C)
Play the Bombchu game in the Market until you get a heart piece for a prize. (C)
When you get the gold scale, go to the scientist hut, and swim to the bottom of the pool inside for a heart piece. (C)
Have Dampe dig until you find a heart piece. (C)
Light all the torches on the ground floor of Goron City, then climb up one level and toss a bomb into the spinning jar. You may have to do this a few times. (C)
Race Dampe again after getting the hookshot and get a time of like, under 1 minute (it seems) to get a heart piece. (A)
In the Graveyard, stand in between the Composer Bros. graves, then pull back the 2nd tombstone in the first row on the left. Drop in, kill the ReDead, then play the Sun's Song. (A)
In the Gerudo Fortress you will see a big chest on top of a roof. Hookshot to the chest and open it for a heart piece. (A)
Play all the songs you know for the frogs (excluding the warp songs), and they will challenge you to a contest. Win and they will give you a heart piece. (C)
When Zora's Domain is frozen, go to Zora's Fountain and hop across the floating ice in the opposite direction of the Ice Cave. There is a heart piece on one of them. (A)
Bomb next to the lone tree by the small stream in the northwest corner of Hyrule Field. Drop into the hole, and swim/iron boots to the bottom for a heart piece.
This is all I can remember for now....check back though, or tell me where one is!
