#1 Idle set
Find the pieces with refresh on it, the more the better. After that, put on regen/-pdt/-dt gear.
#2 Precast
Find pieces with fast cast on it
#3 Max Enfeeble (MND)
Find pieces with lots of enfeebling skill and magic accuracy on it. Then prioritize MND next.
#4 Max Enfeeble (INT)
Find pieces with lots of enfeebling skill and magic accuracy on it. Then prioritize INT next.
#5 Max Enhancing
Find pieces with lots of Enhancing skill on it. The more the better.
#6 Best Healing set
Use gear so your cure potency hits 50%, then prioritize gear depending on your style.
-enmity if you want less hate on your cures
+healing skill if you want stronger cures
fast cast/haste if you want a lower recast
#7.PDT/Kits Set
Find pieces of gear with -pdt on it, or -dt if the value is higher. Don't forget defense. Don't forget movement speed either!
#8.MDT set
Find pieces of gear with -mdt on it, or -dt if the value is higher. Prioritize MDB next.
#9.Special /Ja pieces of gear
If a piece gear augments a JA and it's a desirable effect, leave the piece of inventory and equip it when you use the ability, or when the JA takes effect. Use any of the wikis to find out how the JA works.
#10.Special Augments.
If a piece of gear has a special augment that you want, find out how to obtain it, obtain it, then use it.
Use this site as a guideline, but use you own judgment when creating your sets.
http://myffxigear.kicks-***.org/
Don't forget, 10 fast cast is higher than 5 fast cast and -5DT is more beneficial than -4PDT.
Hope this helps!