Originally Posted by
Sandbar
Rather than restate what people have said above I'll point you to the gear enchancement guide on the maintankadin forum, I am a bit of a newbie tank as well and (just hit 84) I've found that post to be really helpful in choosing what stats to go for and what to gem and reforge into.
EDIIT: well dam, seems I haven't posted enough times to be able to post links, but if you do a google search for maintankadin and goto their forums you'll find it. It's the best gear enhancement guide I've come across.