Im new at this also, and redoing the enemies, items and other stuff is common and welcome.
The ideas I eventually plan on using for Final Fantasy with FFHackster, is to redesign the enemy formations with Tile Layer Pro, and give each one new stats, and also place each enemy in new areas.
The best idea (IMO) is to look at all other hacks for whatever game you choose to edit, and try to create something that hasnt quite been done yet. Invent a new twist that will make your ideas stand out with originality.