I created a deck that almost never fails me.
First, comes 2 0 cards. In the beginning of any battle, quickly scroll past these and use the next cards.
Second, comes around 7 or 8 (i don't really remember, it's been so long) 9cards through 6 cards. I do not allow the keyblade cards to go lower than that. I usually sell anything lower.
Third, comes my 2 potion cards. My HP isn't low enough yet for cure cards, and his HP is not down enough either. That's why I have it like this.
Finally, comes my 3 cure cards. I use these at the end of any of my chains, and I NEVER use them for sleights.
Hope it helps a little.