Once you get the technique down its not all that difficult. This is what I do.
Majora's Mask:
When the battle begins turn into a Zora, walk infront of the mask and shoot your boomerangs which will stun him. Then do a jump attack onto the mask. If you're using the Gilded sword, the Razor sword, or the Great Fairy sword, the other boss masks will come to life. If you're using the starting sword it'll more than likely take two jumping attacks before the other masks come at you (I'm honestly not sure as I always use the Gilded sword). Strafe around the room a lot to avoid getting shot by the beams that masks shoot at you. Shoot down the masks with normal arrows (it takes three arrows to take down one mask, shoot them fast). If Majora does his fire attack reflect the fire with your shield at the masks. Once the masks are gone turn into a Zora again, stun the mask, and then do your jump attack. Repeat until this form is defeated.
Majora's Incarnation:
This form is by far the easiest. Hold up your shield and strafe towards Incarnation. When either he runs near you, or you get close to him do a quick spin, (Don't hold B and charge it up, rotate the movement stick fast and press B. It can take a little while to get the technique down...) After hitting him with a quick spin he'll fall on his face. Run over and do a jump attack. He'll jump off the ground and stand up stunned for another second or two. Quickly do another quick spin and it'll knock him down. Repeat this over and over again and this form will be defeated. (Once you knock him down the first time, he shouldn't be able to get away again... as long as you keep doing those quick spins.)
Majora's Wrath:
Now you use your light arrows. Shoot one at him as soon as you can. Once hes stunned run over to him and hit him with a jump attack followed by a quick spin. He'll jump to the other side of the room, hold up your shield and strafe to dodge his whip. Quickly shoot him with a light arrow after his attack. Then repeat the process until hes defeated.
(When Wrath is nearing death, he'll start throwing spinning tops at you, which home in on you. I honestly just kill Wrath as quick as I can so they don't have time to home in on me... but watch your back.)
If you do this right you can potentially beat Majora with three hearts without even being hit once. Hopefully this helps you out.