(PLEASE NOTE: This video is for my beginner's guide to Final Fantasy)
This video demonstrates the general process for winning a tough battle while showing the functions of the different commands.
(In this video, my party is level 60. I would recommend you be at least level 30 before entering Earthgift Shrine. Even then, if you run into the Abyss Worms, you will be in a world of hurt. Fortunately, they are very rare, and can only be found on the Endless Desert map.)