Building a healer (spell usage)

I'd intended to post a bunch of tips for healing, but there's very little I would add that's not already covered in (the revised) Murderbot's Guide to PvE Healing. I would especially recommend the discussions of the five second rule, cancelling, downranking and healing efficiency. I highly recommend that every aspiring healer read this guide (even for those non-shaman out there, it has some good pointers).

Addition 10/2: For a more generic discussion of what makes a good healer, you may also want to check out The Egotistical Priest's A Good Priest. The comments are fairly priest-centric, but the listing of qualities of good priests applies pretty equally to all healers.

Editted 10/23: New version of Murderbot's guide available on the Elitist Jerks forums.