Its been some time since playing (though when work slows down I will start up agin),

But I used to use a macro on my healadin (will try and find it) That basicly if I had a friendly targeted it would heal that target, or if I had an unfriendly targeted, it then would heal the friendly that target was targeting, and if there was no target would heal it self.. used often for tank healing in raids, would target the boss and with that as soon as it changed targets if someone pulled more agro would already have them targeted to heal them... aswell as would heal the tank when targeted (rarly ever had to actully target the player I needed to heal)