[Quiet Man Cometh]

There is a heart piece in a tree! I found it by happening to looking at up at the right time. To save you some effort, I believe you need the hookshot to get it though the boomerang might work too. I believe it's in an area with a row of trees, like a boulevard. Not sure though.

I find the best guides really are the ones you buy. I have the one for Ocarina of Time and my sisters got one for Majora's Mask. I normally use IGN when I'm stuck but the walkthrough there is pretty much geared to be done step by step so already being in an area can get confusing if you don't start where the guide assumes you should.

Early game has you running around all over the place. Bridges are out, gates are in the way, etc. Takes a lot of wandering around and repeatedly talking to people to figure it out.

If it helps, when you get into new areas you will need to go back into the twilight areas again. Take note of where you see things, because often you will need to back track to go and get them later.