Dungeon 2

 When you go up past the first room in Dungeon 2, you'll find a room filled with Goriyas. You'll definitely want to defeat all of them. When you do, you'll find the Wooden Boomerang.
In the next room, you'll have a chance to test out your boomeranging prowess. You'll notice that the Boomerang instantly kills any Keese it touches (it also stuns most other enemies). Oh, pick up the Compass while you're here too.
In the room filled with Ropes, you can go either left or right. I suggest going left first.
In this room, you'll find the Map, along with two Zols. If you slice them with your sword, they'll split into two Gels. The trick to beating them outright is to attack them with any weapon more powerful than the Wooden Sword. All you have right now that fits the bill is the Bomb (unless you bought the Arrows already), so don't worry about it. Grab the map and return to the Rope room.
Now go to the right to encounter a very subtle hint by the game. Take a Bomb and place it on the north wall and watch a door open itself up.
You did know you can pick up distant objects with the boomerang, didn't you?
In the room filled with Wall Masters, you can Bomb the upper wall to find the Old Man, who will give you a hint on defeating Dodongo. But you have me, so you won't need to do that.
Left of the Wall Master room is a room with a staircase, just like the one in Dungeon 1 with the Bow. You should know how to access the staircase by now.
The passage leads you directly to the boss! Dodongo is very easy, as long as you have Bombs. Just lay two bombs in its mouth and you'll be victorious. Simple!
Huzzah! Two down, six to go.