Warrior - Problem with Garuda NM

[Tashigi]

Tomahawk, then Heavy Swing -> Skull Sunder -> Butcher's Block.

That's really all you need for the normal mode fight IMO.
Amplifying your damage every now and then is nice if you feel your aggro is solid enough but not necessary. (If you look at the little bars below everyone's class icon on the party frame, that's the aggro for everyone on the target selected; Garuda in this case).

If it helps, I recorded this a while back, nothing special, just an average group with a PUG. (Stop the video around 6:45; spoilers).
http://youtu.be/D95Mf7JKCyc

Good luck and have fun