Here are some secrets and generally useful information to help you with the game.
Access Second Quest
If you don't want to play through the first quest to access the second quest the right way, here's a quick way to do so. On the file select screen, create a file and name it "ZELDA". The image of Link next to that file will hold a sword, meaning you can now access the second quest!
Free Rupees
In several hidden caves throughout the overworld, a Moblin will give you a set amount of rupees for free.
You can only do this once per location though, so here's a list of all locations and how much you can get from each:
First Quest Locations:
B1: 30 rupees (bomb north wall to access)
B3: 10 rupees (burn rightmost bush in second row to access)
C2: 100 rupees (burn northmost single bush to access)
D7: 30 rupees (bomb wall left of stairs to access)
G3: 10 rupees (burn southwest single bush to access)
H2: 30 rupees (bomb north wall to access)
I4: 30 rupees (burn northmost single bush to access)
I6: 30 rupees (burn south bush in second row to access)
L2: 100 rupees (burn south bush in second row from right to access)
L3: 10 rupees (burn south bush in left row to access)
N5: 30 rupees (defeat left Armos to access)
N6: 30 rupees (bomb wall right of stairs to access)
O4: 10 rupees (defeat right Armos to access)
P8: 100 rupees (walk through north wall at P7 to access)
Second Quest Locations:
B3: 10 rupees (burn rightmost bush in south row to access)
C6: 30 rupees
D3: 100 rupees (burn south green bush in left row to access)
D7: 30 rupees (bomb north wall to access)
G3: 10 rupees (burn south bush in leftmost row to access)
I3: 30 rupees (use Whistle to access)
I4: 30 rupees (burn right bush in upper-right corner to access)
I6: 30 rupees (burn south bush in right row to access)
L3: 10 rupees (burn south bush in leftmost row to access)
L6: 10 rupees (use Whistle to access)
N5: 30 rupees (defeat right Armos to access)
N6: 30 rupees (bomb wall right of stairs to access)
O2: 10 rupees (use Whistle to access)
O4: 10 rupees (defeat right Armos to access)
Quick Save
To save your game without having to die first, press Up and A on the #2 Controller to bring up the "Continue, Save, Retry" menu.
Refill a Red Water of Life
If you bought a red-colored Water of Life and use it once, it turns blue, meaning you can only use it once more before it disappears. To refill it from blue to red without wasting extra money buying a Red Water of Life from the Old Woman, simply buy another Blue Water of Life. That will make the blue one you had turn red, giving you 2 uses out of it (the way 2 blues make a red is beyond me).
