OK, I'm not usually one to use tired old catchphrases, but forgive me, I'm going to use one right now: You are not prepared. That pretty much sums up Cataclysm heroics, especially as they are now on beta. Chances are, you've grown used to the easy stuff we have in Wrath. Not only are Wrath heroics a little underbalanced, and not only have patches specifically made them easier and faster to run, but at this point, we're running things in tier 9 and 10 gear that were made for people in pre-tier 7 gear, and we're steamrolling them.
All this ends with Cataclysm heroics. I cannot stress this enough. You see that picture up there, at the top of this article? You'll be seeing that a lot. Cataclysm heroics are hard. They are hard enough that the random dungeon finder may end up being something you want to avoid in favor of creating your own group so that you can work together and get the proper balance of crowd control and skill. While some of the difficulty comes because we'll all be in dungeon blues, some of it is because the dungeons are genuinely set up to be harder, with harder-hitting mobs and bosses with mechanics that require you to use utility moves to have a chance of beating them.
With this in mind, I have a few tips for you on getting ready for the new heroics. Trust me, you'll need them, if you don't want to spend all day wiping to the first trash pack in your first random heroic.