When you level-up, you will be given the option of boosting your attack/defense, HP, or magic. One of the three will give you a larger boost than normal. How do you know which one to pick?
The answer is fairly simple. Divide your new level by 3 and take the remainder. If the remainder is zero, you'll get the biggest boost by choosing "attack". If the remainder is one, you'll get the biggest boost by choosing "HP". If it is two, you'll get the biggest boost by choosing "magic". This establishes this pattern:
- Level 2 (remainder 2): Magic
- Level 3 (remainder 0): Attack
- Level 4 (remainder 1): HP
- Level 5 (remainder 2): Magic
- Level 6 (remainder 0): Attack
- Level 7 (remainder 1): HP
- Level 8 (remainder 2): Magic
And so on: Magic, Attack, HP, cycling over and over. You can also remember which one you chose last for that particular character (if it was the correct one) and simply choose the one over to its right. For instance, if you chose HP last, then you should choose "magic". If you don't remember what you chose last, well, now you know how to figure out what to choose. :)
If you're not sure and you can't do the math in your head, you can simply look at each attribute. Go to "attack", press to see how much it gets boosted. If it doesn't look like a big boost (only one point), press to cancel and choose "HP", and so on.
Of course, you don't have to follow this pattern, but it will likely lead to the best results.
Experience in Super Mario RPG: Legend of the Seven Stars is fairly simplistic. Enemies start off giving one experience per kill, so the overall grind isn't very long. High levels aren't necessary to completing the game, but if you want to figure out the best way to level, you should optimize your tactics based on your character levels, play style, and amount of experience gained per level. The following table displays the required Experience Level to get to the desired Level.