After you get Din's Pearl in Dragon Roost Cavern, you go to your next destination: Forest Haven.
Make Some Preparations
After you land at the Forest Haven, get back into your boat and cruise around to find the fish guy that's jumping around to get this area marked on your sea chart.
Also, I had mail when I arrived here, so be sure to check the postbox.
If you don't have any hyoi pears yet, go to Beedle's shop ship and buy some.
Go into the Forest Haven
Now go up those ledges near the postbox until you encounter a boko baba. To kill it, lock onto it, stay back, and press A to do a jumping attack with your sword to make it point up. Then hit the exposed stem. Boko babas drop seeds, which you can use here in the Forest Haven to get blue potion.
From there, head right, kill the boko babas, go up the ledge, kill the boko baba there, then swing over to the little rock outcropping. To do this, you will probably have to change direction on the rope by holding the R button. Once you land, get your shield out right away to deflect the octorok's rocks. Its rock will bounce off your shield and hit it. Then jump to the outcropping to the left, kill the boko baba there, and jump to the little island in the middle of the water. Climb the ledge, jump to the next rock, then get out your shield again to defeat another octorok. Then grapple into the little pool where the octorok was, and go inside.
Help the Deku Tree
Head right, climb up the waterfall, keep going around and up another waterfall, and you'll reach the Deku Tree. Get close to it, and chuchus will appear all over it. Do a rolling attack into the tree to knock off all of those chuchus, and kill them all. There might be another one on the tree's face after that, so just do another roll attack and kill it, then watch the scene.
Catch a Firefly
The Deku Tree will make a leaf appear way up in its branches for you. Before you go up there, empty a bottle if you don't already have an empty one, then look around in the grassy areas near the walls. Eventually you will see a white/blue bright spot. It is even brighter than most of the glowing spots here, which are just yellow. Catch the bright white/blue spot in your bottle.
If you want some potion made from your boko baba seeds, go up the hill to the right of the Deku Tree and into the door. Hollo will make potion if you have an empty bottle and 4 seeds.
Get the Deku Leaf
To the left of the Deku Tree, ther is a purple flower bud called a baba bud. Get into it and it will shoot you up into the air. If you don't touch the D-stick, the bud will just shoot you straight up, and you'll land back in it again. This is very helpful if you're not sure if you are aimed in the right direction.
After you get into the bud, aim with the D-stick, and when you're facing the correct direction, hold up on the D-stick and the bud will shoot you forward. You can also hold down on the D-stick if you want to go backward, but you shouldn't have to do that. Jump from bud to bud. Eventually you will get into a bud and won't see another bud nearby. Above you, there is a branch with leaves on it you can land on from the bud. From that branch, grapple onto the branch above, change directions if necessary, and swing to the next bud. Jump from bud to bud until you reach the Deku Leaf.
To use the Deku Leaf, jump into the air and use it to glide down, but be aware that this consumes magic. If you are outside, be sure to change the wind direction to whichever way you want to go, because otherwise you will get blown off course. If you are gliding, press the deku leaf button again to bounce the leaf, which can sometimes get rid of nearby enemies. There will be many situations where gliding is necessary to proceed, so don't forget to try it if you are stuck. If you're standing on the ground, use the deku leaf to blow a gust of air. This can disable some enemies and can turn some special switches.
Open the Figurine Gallery
The following part is optional. You can start the figurine gallery sidequest now if you wish. If you would rather skip this, then go to the bottom of the Into the Next Dungeon section.
After receiving the Deku Leaf, you can reach the figurine gallery. For now, ignore where the korok tells you to jump, and instead, jump and glide to the bud that is farthest from where that korok is standing. Baba buds replenish your magic, so if you're low on magic, just keep the D-stick in the neutral position and you'll repeatedly land in the bud, replenishing your magic. Then, press up on the D-stick so you go forward, and at the peak of your jump, use the deku leaf to glide over to the ledge up there. Get into the baba bud to replenish your magic, then go out.
When you play the Wind's Requiem, a compass appears above Link's head. You can have Link face the direction that he wants to go, then play the Wind's Requiem. That way, all you have to do is turn the compass to point in the direction that Link is facing, and that will make the wind blow in the direction you want to go.
Have Link face the little island down below that has a big hatch, and change the wind to go in that direction. (Read the previous paragraph again if you don't understand how.) Then use the Deku Leaf to glide down to the little island.
Once you are on the island, turn around, use your telescope, and look at the island that you just jumped down from. In a little indentation in the wall, you will see a white switch. To hit that switch, use a hyoi pear to take control of a seagull. Turn the seagull to face the island you jumped from, then tap A to make it flap its wings. Steer with the D-stick. Have the seagull fly into the switch to activate it. The hatch will open and the ladder will drop. Press R to switch back to Link, and jump into that hole you just opened. This is the figurine gallery that I mentioned earlier in the walkthrough. You actually can't do anything in here yet, so just go back out for now. Your boat will be waiting for you at the base of the ladder.
To start the figurine side quest, you must return to Windfall Island. Before you go to Windfall, make sure to catch a firefly and open the figurine gallery first as described above. Your boat won't let you go in a straight line to Windfall from here, so change the wind to N and go back to Dragon Roost. From there, change the wind to W and go to Windfall. On the way, you will pass Pawprint Isle, which you can get added to your sea chart. You can visit the island if you want chu jelly, but there isn't much else there. Continue and land at Windfall Island.