Hyrule Courtyard Friends
When your young Link and first sneak into the castle to talk to Zelda, before you go see her walk to the right (as soon as you walk into the courtyard facing Zelda) to the window. If you look through the window you'll notice pictures and paintings in some room with Mario, Bowser, Luigi, Yoshi, and the Princess! Stand to the right of the window and use the up C button to look at Yoshi, look at Luigi and if you shoot the window with your sling shot you'll get a Red Rupee.
Catch a Butterfly
Whenever you see butterflies, you can whip out your Deku stick and carefully place the end on the butterfly. If done correctly, the butterfly will turn into a fairy, and you can catch it with your bottle. It is quite hard to do, but it is possible. If you are having trouble, try swinging your Deku stick at the butterfly.
Lost Woods Path
When walking through the Lost Woods and are not sure if the path will send you back try this trick. If you walk up to a path that has brown in the middle it will send you back(unless it is the Sacred Forest Area). If it is just a black background, you can walk through it.