This one goes into a lot of detail.
http://forums.d2jsp.org/index.php?showtopic=19782009&f=272basically, get HM on all of your gear, HM+Int if you can afford it. also, get a high HM charm in your MAIN slot, HM+INT if you can afford, and the highest EE heal you can afford in your ACC slot.
with all the HM+Int gear, you will be healing a ton, which is what a guardian's job is. tank+heal.
hope this helps!
EDIT: this build is not cheap! heal mastery/int gear is well sought after, so this can be a FG intensive build. good luck, and if you have any more questions feel free to PM me.
This post was edited by jlhromeo on May 27 2009 10:49am