Ok, after some goofing around with my macro, I added a new qualifier::
/cast [help] [target=focustarget, help] [target=targettarget, help] [target=player] Renew
One of my problems was relying on mobs picking my targettarget to heal, without that bold addition. Or having to hit the "/assist /follow" key to get the toon to heal which would spin guys around and maybe make them move and break casting. Of course I could have made another macro "/assist" without the follow... but I'm kinda happy with my noob self thinking through a mod to this one . Of course it seems so obvious now.
/facepalm