Hey - I began WoW about 4 months ago, and am pretty new to tanking. When gearing up, I tried Mechanar as 'the easiest heroic' and basically figured it out mostly by myself. Here is something I discovered that you might wanna add to your heroic Mechanar guide:
With the little demon bombers who deal arcane damage and simply attack the closest party member: there is also a delay before their attack hits, and it doesn't target players. AKA if you run through them TCing and keep moving, you will get hit by barely any bombs and the DPS can basically go wild and have fun.
Other than the occassional response to a particularly overzealous DPS this strat worked a lot better than anything else I found and could be pretty useful to newbies and old timers alike.