You must be new to Final Fantasy...

Just keep playing and you'll eventually max out your character(s). I seriously doubt you'll be getting 9000hp when you're what, the first disc?

My tactic for pretty much all RPG games like FF is

1. Stock up on as many healing stuff as you can. Even if you're really weak, you can just keep healing yourself, and you'll eventually beat the enemy

2. Level up. If you find an area with particularly high XP given from enemies, spend some time levelling up in that area, it makes everything else so much easier.