If you played Ocarina of Time you should remember the Gold Skulltulas.  In this game there are two places where you will find these critters.  They are in the Swamp Spider House of the Marchlands near the Deku Palace and in the Oceanside Spider House on the Great Bay shores.  In each you are asked to kill 30 Skulltulas and retrieve the tokens they leave behind.

Swamp Spider House

Use a deku stick to burn away the web and begin this quest.  To heal the cursed man you must gather all 30 tokens and as your reward, he will give you the Mask of Truth.  Since you don't need any late-game items, this can be attempted at any time.  All you need to complete it is the Deku Mask, the Sonata of Awakening, and a couple of Magic Beans.

• 1, 2, 3
  The first three are a cinch to catch.  #1 is just piddling about in the pool.  #2 is in a pot near the stairs.  Lastly, #3 crawls up and down a pillar on the west side (hit him when he is low if you don't have a Hookshot).
• 4, 5
  Both of these Skulltulas are hiding in the bean spots.  The flush them out, go back to the first room and catch some bugs in your bottle.  Release them near the bean spot, and they'll burrow in kicking the Skulltulas out.
• 6, 7, 8
  Head east into the next room.  You'll find one Skulltula in the small pots, and two more in the big pots on the east wall.  To get the Skulltulas out of the big pots, use your Forward Roll.
• 9, 10, 11, 12
  Play the Sonata of Awakening for the sleeping Deku, and he'll abandon his flower.  There is one Skulltula in the tunnel near him (cut the vines that block the tunnel with your sword).  Another is on the higher level of this room, which can be reached using the Deku Flower.  Then use Deku Bubbles to shoot down the hives on the ceiling for two more Skulltulas.
• 13, 14, 15
  There are three Skulltulas in the upper level of the main room.  #13 is in the bean spot, so use bugs again.  #14 on the far wall is trickier.  You'll need to shoot it down and use the Deku Flower to claim the token.  #15 is on a pillar in the other side.
• 16, 17, 18, 19
  From the top of the main room, head into the west room.  You'll find one Skulltula by the torch in the corner, and another on top of the metal thing in the center (use a Rolling Jump to get the token).  Two more await in the crates on the ground level (smash them with Forward Rolls).
• 20
  The get the Skulltula skittering beneath the catwalk, bomb away the rock in the corner to uncover a bean spot.  Plant and water a Magic Bean, and ride the petal to the Skulltula.
• 21, 22, 23, 24
  Enter the north room via the door on the higher level of the east room (where the sleeping Deku was).  Hit the crystal switch to make a ladder appear, giving you access to Skulltula #21 and the bean spot.  #22 is on a nearby pillar.  #23 is in a hive on the ceiling.  Plant and water a Magic Bean in said bean spot to get to Skulltula #24 and make an easy route to the lat room.
• 25, 26, 27, 28, 29, 30
  There are two Skulltulas in the deep grass that surrounds this room, and a third in a hive on the roof.  The final three are all in the tree, and you'll need to hit the trunk with a solid roll to knock them out of it.

The man at the entrance will now give you the Mask of Truth.  You have then completed the Swamp Spider House.

Oceanside Spider House

Compared to the the Swamp Spider House, this is a bit tougher.  The reason for this is that it needs to be completed during Day 1 to get the Giant's Wallet.  On any other day the prize is just rupees.  You'll need to bring the Fire Arrows, Hookshot, and some Bombs.  And since time is essential, play the Song of Inverted Time before starting.

• 1, 2, 3
  These are all easy to get.  There are two Skulltulas in the tunnel.  The third is behind the gate.  You'll need to burn away the web with a Fire Arrow and use a Hookshot to get the token.  Then use the Hookshot target in the ceiling to pull yourself over.
• 4, 5, 6, 7
  Use your Hookshot to nail a Skulltula on the ceiling rafters near the entrance.  #5 and #6 are in the pots (burn away the web, then Forward Roll into the pots).  Lastly, #7 is hiding behind one of the masks near the stairs.  It'll poke its head out every now and then.
• 8, 9, 10, 11
  This is where things begin to get a bit tricky.  Start with #8, which is hiding behind a picture frame (hit it with your Hookshot).  Then go to the three small dressers near that and pull the south one further south, the north one further north, and push the middle one in any direction to reveal #9.  #10 and #11 are simpler: just push aside the bookcase in the south side of the room to reveal both.
• 12, 13, 14
  Shimmy up the empty shelves of the "climbable bookcase" and scan the crack between the top of the wall and the ceiling for Skulltula #10.  You'll find #11 atop the bookcase in the opposite corner of the room, and #12 in a tight passage behind a painting (you need to be on the bookcase right across from it to get the right Hookshot angle).
• 15, 16, 17, 18, 19
  Stop halfway down the stairs to this room and scan the crack between the ceiling and the east wall for Skulltula #15.  You'll find #16 in the big pot by the torch near the north door.  #17 is in the little pot atop the crates in the corner.  #18 is in a mask behind the stairs.  Burn away the web on the west wall and peek into the crack to see #19.
• 20, 21, 22, 23, 24
  Burn away the web and head south.  Roll into the crate on your right to reveal Skulltula #20, and hit the crate on the other side to reveal a passageway to #21.  Shoot a Fire Arrow at the ceiling web on your left as you exit, and use your Hookshot to nab #22.  Climb up the crates on the south wall and look to your left to see #23 hidden behind the canoe(?).  Then climb up the crates near the hidden passage and head north.  When you have a clear shot, Hookshot to the barrel on the rafters.  Break open the other barrel up there to get #24.
• 25, 26, 27, 28, 29, 30
  There's a Skulltula in the ceiling crack near the door, but you'll need to stand on the table to get a good shot at it.  The next two are easy: #26 is in the big pot in the corner, and #27 is behind the painting next to it.  To get the final three, use your Goron form to do a Goron Smash in the middle of the table---etiquette be damned!

After collecting the last token, head to the front to receive the Giant's Wallet (or rupees) to complete the Oceanside Spider House.

In this Spider House is a Heart Piece.  If you use your bow to shoot the four masks in the dining room in the right order, a passage to it will open.  Each Stalchild knows one part of the code (there are six total...Don't forget the two in the library), and they will tell you if you wear the Captain's Hat.  Or, if you have lots of arrows, trial and error is also good.