You have the option of making a Pyromancer/Geomancer suit FFXIV Gold

The Crystal Desert Levels 18-20 - You now arrive in Amnoon Oasis. Have a look around town and grab the quest here. There’s an Armor Crafter here and if you have the FFXIV Gold and materials then I would suggest upgrading. 

The mobs in this area primarily deal earth damage and fire damage. So you have the option of making a Pyromancer/Geomancer suit.

The majority of caster damage is earth, so crafting the Geomancer robe is a good move. You may want to craft Pyromancer pants, but the mission mobs specialize in Earth while the non-mission area mobs (namely hydras) specialize in Fire Magic. 

Therefore doing the Geomancer robe/pants combination is likely a wiser choice for missions; a Pyromancer one being better for farming. As far as the gloves and boots are concerned, doing Pyromancer would be helpful, but not particularly needed. You may want to explore a bit and test the damage yourself before making any final decisions.

From here, head south and follow the road east. You’ll stumble across Maguuma Stade. Once done here, zone out and head east; then work your way north along the trails.

Before giving you directions, I’ll mention there are collectors here in the desert with top-level items.