I ran a heroic 30 minutes after hitting 80. But being a pre-WOTLK tankadin I knew how to gear. I had my 540 + over 22K health/armor using 2 engineering trinkets. Got lucky on some drops picking up lvl 80 heroic blues/purples. By the time I had 1 day played at 80 had nabbed my libram, badge neck, def ring from a NAXX 10 boss, and shield from 1st run through H COT: Strath.
This site helped alot on the way there. Don't wait till 80 to start reading up on your class and spec... if you do... Here's your sign.
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80 - Prot - Strormrage
http://www.wowarmory.com/character-sheet.xml?r=Stormrage&n=Hardydefense
Raid Tanked: Naxx 10 - Spider wing cleared