Visit the shops in towns often to make sure you have the most up-to-date equipment. Make sure you've equipped your characters properly with all the necessary armor, weapons, and other equipment.
If you want more- like maps of each level, complete lists of every monster, spell or magic item, and much more detailed combat strategies, then check out Final Fantasy Tactics: the Official Strategy Guide. We've also included the basics of combat and magic. In the Prima Fast Track Guide for Final Fantasy Tactics, you will find the tips and strategies necessary to complete the almost 70 challenging battle maps of this great game.