In Burning Crusade, heroic difficulty was basically on par with Kara (early T4 content).

It makes sense for Wrath heroics to be on par with Naxx 10.

If you're not ready for one, then you're not ready for the other as well.
That is not to say, its not worth trying more, as you'll learn the tactics and the correct responses will become instinctive over time.
Upgrade your gear from non-heroics and any questline that has gear which is an upgrade.

For early Kara play, when no one had T5/T6 level gear to carry someone else's alts, everyone needed full blue gear or the green gear that should have been blue (a lot of Feral gear for example) before the raid had a chance to progress.
With a boxing team starting heroics, the lowest denominator applies. None of your toons overgears what you're doing, so they all need the best gear they can have to succeed.

If you can beat a few bosses already, farm the crap out of them every day. The badges will add up, and result in a significant upgrade in a couple of weeks.
The bosses which you are closest to beating are the ones to focus on, try them daily, you'll eventually get them and increase your badges per day for your team.
You'll reach a point for each boss, where suddenly the fight is winnable where before it was not -- that is a rush.
In the meantime, seek out upgrades as you can and you'll be moving in the right direction.