I wrote a few tips in this thread:viewtopic.php?f=19&t=2216&start=10#p20216
(quoting it below)
However the most important thing to getting challenge modes down is knowing the right tactics for each dungeon. Like which packs to skip, where to use invis pots and how to handle certain mechanics so they work in your favor. If you need tips for a specific one, feel free to ask.
Made all gold today as as Blood DK, Shadowpriest, Fire mage, Elemental shaman and Restodruid.
Have a Voidshift macro for your tank. Sometimes he just get gibbed instantly before he can catch a heal, and this macro WILL save you quite a lot of wipes.
Mine looks like this:
/cast [@tanknamehere] void shift
/cast desperate prayer
/s << Voidshift on tankname! >>
Have it on a bind where you can react fast.
As for talents, I specced Twist of Fate and Halo for most dungeons, because of the very high uptime on it. I can't see any of the other talents being better, ToF wins by a mile. For 90 talents I took Halo for the most part but certain instances doesn't allow for using halo (like scarlet monastery), so I had to use Divine Star. I didn't use cascade much as it does pretty bad single target and it actually has a risk of pulling everything in sight, such as the first pulls in SM, so I didn't really use it. Also Halo is really good for the extra group healing.
I used glyph of VE in all of the challenge modes, and it was a true lifesaver. Having an on demand raid healing cooldown was indispensable. We relied on that a lot on many pulls. Glyping it makes it more bursty, and do 25% more effective healing than non glyphed. Definitely a taker.
Used Glyph of Mindspike on most other pulls due to using FDCL. In instances where you have to spam mindsear a lot (SM again), you dont get to use Mindspike a lot, so I ran mindbender instead and swapped out the mindspike glyph for Psychic Scream, for the extra aoe interrupt, which is very helpful on the big caster pulls in cathedral and after the first boss.
Last glyph was usually Dark Binding, so I could help healing without losing an extra GCD to go back in form. In certain instances I had to change dark binding to Mass dispel, like scarlet monastery (to dispel fanatics), and Jade serpent (for the courtyard pull, or the Sleep debuff the bird does in the library).
But VE, Mindspike, Dark Binding was my stable ones, and Mass Dispel and Psychic scream was situational. Mind Flay is also an option, I used it in instances where I didn't need to heal, and we needed all the dps we could get to make the timer, but not a lot of room for it so I usually swapped it out.
A last tip; there are some bosses that you can comfortably respec on before entering combat, such as the endboss in Setting Sun, Brewery and Shado-pan, and others and I suggest swapping to Power Infusion on those. Twist of Fate isn't very good for bosspulls, but Power Infusion is great as it is a high burst cooldown, and it will give you some extra seconds on your kills, especially when stacked with potion and bloodlust. If your group allows it, keep it in your bag of tricks if you need to shave off some time. Just remember to rebuff Inner Fire before you pull.