Challenge Modes are a great new addition to the game, I've spent a huge amount of time in them since MoP launched, but I've also noticed that a lot of people give up easily because the initial brick wall to figuring them out can be daunting. I want more people to enjoy and discuss these modes! They're a lot of fun
To that end, I've put together walkthroughs for all of the current dungeons so that groups starting a dungeon can have a reference to start with and adapt the strategy to their group, reducing some of the frustration and initial hurdle of learning what you can and cannot skip, which trash is hard, etc.
Some basic tips that hold true for all challenge modes before you start:
Consumables! You need these. There are:
18 second Invisibility Potions, that take 1 Ghost Mushroom and 1 Sungrass each.
15 second Lesser Invisibility Potions that take 1 Wild Steelbloom and 1 Fadeleaf each.
Flasks - Tanks should use DPS flasks
These represent a lot of the tank damage you will take during Challenge Modes, because you can't afford to CC most of the time and you often have to pull multiple packs together. The way you best handle these are by coordinating large tank cooldowns, smaller tank cooldowns, large healer cooldowns, and soft CC (interrupts, stuns, disorients, etc). For example, with my group a pretty standard 'hard' trash pull would involve a shadowfury on the pull, while I start a remorseless winter, leading to an extended stun while the DPS is AEing hard, then if there are casters that need priority interrupts we will have one person on each (or multiple on one as the situation warrants) and interrupt them while AE'ing the trash. If not enough is dead when stuns wear out, the tank will pop a big cooldown like Icebound Fortitude, or a healer cooldown like Tree of Life. Every party has a different composition, this is going to be the most challenging part to figure out. Once you know what you can do to keep a group mostly controlled for 30 seconds at a time, you will be much more successful in Challenge Modes.
Typically bosses are not a huge hurdle in Challenge Modes, trash represents bursts of intense difficulty, while bosses test your ability to sustain high dps and mechanical aptitude for longer periods of time. Bosses are typically where you will want to use cooldowns like Doomguards and Bloodlust/Heroism, but in some instances trash packs are good places for these as well.
Healers should be drinking before you pull any trash pack or a boss, mana is a huge issue and spending 2 seconds getting out of combat can save you from wiping when your healer goes OOM at the last 10% of a fight.
Guides for individual dungeons, listed in my personal of easiest to hardest:
Gate of the Setting Sun
Temple of the Jade Serpent
Siege of Niuzao Temple
I won't make any claims that these are the most efficient routes, but I know there are a lot of random videos and it can be hard to sort through to find good information on a few of the zones, so these all are at least a great jumping off point on your quest for Gold times, and maybe you'll start to think of your own tricks and take world first