Here are the best/most popular enchants to use on your Discipline Priest. There are multiple choices for some slots, just use your best judgement on these for what stats you are lacking in right now.
Legs - Powerful Ghostly Spellthread
Shoulder - Greater Inscription of Charged Lodestone – requires exalted with Terazane
Head - Arcanum of Hyjal – requires revered with Guardians of Hyjal
Hands - Enchant Gloves – Haste
Off Hand - Enchant Off-Hand – Superior Intellect
Since you’ll need to be exalted with Therazane in order to get the Greater Inscription of Charged Lodestone you should pick up the Lesser Inscription of Charged Lodestone when you hit honored and upgrade once you are exalted.
Also, technically an enchant, is the Ebonsteel Belt Buckle, be sure to get one and socket it.