Gosh, this dress was a labor of love for me, I hope yours comes out beautifully!
I didn't use any patterns for my dress, but what you're aiming for as far as the top part really is just a sleeveless shirt with the addition of the squared off collar, so that's basically how I did mine (made a sleeveless shirt with a zipper on the side and then sewed on the collar, hah!).
I hope you use a circle skirt for the bottom of the dress! Zelda's dress is depicted as having a LOT of folds and fabric in it, I think a circle skirt is one of the best ways to go about this, and they are easy to make. I used a circle skirt and the way my skirt lays is one of the most common complements I get on the costume!
The over bodice is easy enough, just be sure to keep it symmetrical and not to make it too long.