Through my experiences of healing for 5 man dungeons and raid healing 10 and 25 man, I have found that discipline healing is very similar to druid healing.
Druid healing you want to take the time to pre-heal key people that are going to get hit.
Discipline you want to do that but you'll also want to take into account that when you bubble someone and that bubble is dispelled or used up that you will get 2.5% of your mana back thanks to Rapture. But there is a internal cool down that prevents you from always getting mana back. The trick is to time it so that all of your bubbles fall at the same time so that you "beat" the internal cool down.
In 5 mans, I tend to bubble everyone but the tank since he's most likely to punch through the bubble. A good example will be the first boss in heroic Gundrak, Slad'ran. When he is going to poison nova everyone. You bubble everyone but the tank.... nova.. and then you watch your mana bar go up 2.5% x 4 = 10% mana back :)
In raid healing, Discipline shines on the nasty raid wide damage that you can pre bubble everyone. A lot of the ICC fights like Festergut is setup for you to just go bubble crazy and wait for the blight to hit.
Unforntunately healing as a disapline priest means you give up alot of your healing potential since you can't take Spiritual Guidance. Well you could if you give up penance and a few fun talents. 25% spell haste is quite nice from Borrowed Time.
Discipline has a lot of patterns that are easy to get used to. Power Word: Shield (tank) -> Penance (tank) -> Prayer of Healing (group). Penance will gain the 25% haste from Borrowed Time but will not use it up. Then you can use Prayer of Healing with the 25% haste buff and push it out faster.
Another useful combo, is bubble up the group members and cast prayer of healing with inner focus (makes your spell free and increase crit chance) then spot heal with penance and flash heal.
