I would suggest also doing the 'easy' bosses in an instance when you are first starting and then moving on to the next one. Like doing the first two bosses in slave pens and then hungarfen in underbog(the pull before him is harder than he is on heroic). That way you can start getting badges and some gear without banging your head against the wall. Also the trash before the final bosses always tends to be harder and more of it. For instance mana tombs is just a ton of trash after the second boss. Sethek heroic was also nerfed pretty hard after they put the Druid epic flight form quest in there so that is another good place to start.