Melia: Somewhat Good Strategy
Melia is a good asset to the team. She starts with lightning, fire, and water, along with other moves like hypnosis, a move that keeps your enemy still and some others. If you use her, cast her water spell first, it gives the party regenerate: health automatically restores a little bit over a period of time. Stay close to your party, otherwise the effect will only be for her. Best way to stay alive if your team gets hurt easily.
Unrelated Quest (s)
When I first started the game, I didn't expect to receive so many side quests. My advice is to do them all. They're time consuming, yes, but worth it in the end as far as XP and money goes. Also, the skip feature makes it a whole lot quicker to jump from place to place.