Is my tank and team geared enough to begin heroics?

[Bigfish]

Could be your healer too. Heroic healing is MUCH different from normal healing. Burst damage (incoming) is significantly higher in heroics.

Having a healer that can heal normally for 7k and crit for 10k is where you want to be. My resto Shaman crits for 12k quite consistently these days.

Just to expound on this, healing different heroics and raids involves a HUGE differential in how you have your healing macros set up. I would argue this largely arises from our tendency to overheal normal 5-mans, and so we expect heroics to just use some of that excess healing.

Of course, among other things, some fights are easier, and some are harder based on set up and tactics. The important thing is to get whatever you are fighting down. Once you can do that, you should improve naturally.

That said, there is no surefire way to decide the cutoff for when it is appropriate to do heroics. In that regard, heroics are also not your first step on the loot train once you hit 80. You can literally gear an entire team in craftable gear and quest rewards, and in my opinion you should be pretty decently far in to doing so before you start working on strategy over gearing.

Of course, that's just my 2 cents on gearing in general. I only ever dropped 2 bosses in Heroic UP, and now I just farm Naxx and Archavon for badges.