The journey to Hyrule Castle begins when Link exits the Kokiri Forest. Saria will interrupt Link as he crosses the bridge to exit the forest and express her undying love for Link… or maybe that they will just be friends forever. She will provide Link with the Fairy Ocarina as a parting gift.
You regain control of Link once you reach Hyrule Field. Walk down the pathway and you will run into an owl sitting on one of the tree branches. This is one of the most painful parts of the game – there is no way to skip the owl’s extremely long monologue.
As explained by the owl, the pathway leads directly to Hyrule Castle. There is not much that you can do in Hyrule Field currently, but wait until night time (you will know that it is officially nighttime when you hear a wolf howl sound effect), and then re-enter th Kokiri Forest.
There is a hidden 
Gold Skulltula in the Kokiri Forest that you can only see when it is nighttime – and just as a side note, the time of day only changes when you are out on Hyrule Field. The Gold Skulltula can be found on the back of the Know-it-all-Brothers house, which is the one in the southeast section of the Kokiri Forest (number 4 of 100).
The next side quest you can do involves traveling through the Lost Woods to obtain your first Heart Piece. Check out the links below for more information:
Big Bullet Bag (Lost Woods)
Head into the Lost Woods to obtain a larger Bullet Bag to store more Deku Seeds for your Fairy Slingshot.
Deku Sticks (Lost Woods)
Buying the Deku Sticks upgrade from the Business Scrub in the Lost Woods.
Heart Piece (Lost Woods)
Play the memory game using your Ocarina of Time with the two Skull Kids in the Lost Woods to obtain a Piece of Heart.
Head back to Hyrule Field once you have completed all of side quests and tasks listed above.
Note: You can avoid battles against enemies on Hyrule Field at night by staying on the pathway. Enemies only appear once you venture off the pathway. Fans of the series will recall that this same mechanic existed in the original “The Legend of Zelda” and “Zelda II: The Adventure of Link” on the Nintendo Entertainment System (NES).
Hyrule Field is huge and there are a number of areas that you have access to, but most of the areas including their side quests cannot be initiated at this point in the game. Follow the pathway through to Hyrule Castle which is located on the north side of Hyrule Field. The drawbridge will be closed if you approach the castle at night – just wait until daybreak for it to open again.
Before you enter the castle proper you will find yourself along a walkway with a doorway on the north side. Go through the doorway to enter the guardhouse which is jam packed with pots. Break them all open to earn a few easy Rupees. You will need these Rupees for a few of the side quests that are available in the Market.
There is also a Gold Skulltula in this room in one of the crates – roll into the crates to break them and pick up your next Gold Skulltula token (number 5 of 100).
