Spriests are even MORE technical now to get right. Here is what i've learned in Cata. Suggestions welcome...

Open w/ SW:P, then VT. Others claim VT first but I like SW:P as it helps to proc a shadow ball. Flay until shadow ball. With luck, you get one. After four flays w/o, give up, cry and spam DoTs until you run out of mana. ... i.e. typical Wrath style other than keeping empowered shadow up. Empowered Shadow: because we need ONE MORE THING TO WORRY ABOUT.

Odd tips, new in cata:
* Forget about focusing down one mob unless it is a very specific fight. you aren't that type of DPSer.
* studder-step after a mind flay. helps to proc an apparition
* when spamming DoTs, open with SW:P, then VT. While casting VT, tab or click for your next target. if you open with VT, you waste time when looking for the next target.
* I can't manage more than 3 or 4 dotted targets. If you can, good for you. You manage stress better than me.
* Return to targets to flay and, hopefully as it is random now, refresh SW:P.
* you can clip your last tick of a DoT now. So, recast a bit early for better effect.
* SW:D isn't for end fights. when running or when something isn't going to die for 10 seconds, cast it for instant damage. In most fights, your own regen will heal you so long as you don't stand in fire, mobs don't have a weird ability and the tank keeps aggro
* Dark angel whenever possible for mana regen. helps flay increase damage too but like you want to manage ANOTHER over-time action.
* At end of fights, don't use your balls. Save em for the next fight so you can open with a Mind Blast and get Empowered from the start. This reduces your ramp-up time.
* Shadowfiend is in play. Use whenever possible as there are lots of ways to reduce its cooldown in a fight. Don't save for bosses.