Ill add some tips too.
Keyblades: try to use the best possible keyblades for each world, example: after you get the Mulans world keyblade(forgot name:P), you can take the star seeker off valor and use it since at that point its a useful keyblade.
Items: If your running low on Hp and your out of MP, items are your best friends especially since in kh2 you can shortcut items unlike in kh1.
Abilities: Get used to using abilities since you will need them throughout the game, i wont go into detail on any abilities but in the beggining of the game if you had to choose from guard or scan, id choose scan, youll see why when you play it.
