I loved how OP is being active in this thread instead of just creating it and leaving.

Everyone is giving healing and damaging tips, so I would love to throw out a bit more about being a healer and how you can position yourself.

To be a healer on FFXIV is is to be a tactician, as the Nymian scholars would instruct you. Even this being a Scholar-ish lore point of view, you can really apply it on any healing job. Know your job, know everyone else's job. Communication and experimentation is the key of being a good healer. Talk with your party, specially your healer partner when doing 8-man groups. Try different ways of healing each mechanic and use the one you feel its more comfortable to your party while being comfortable for you.

Even though you can get some tips about healing, its not about a recipe like how you should do a rotation. Remember to experiment, preact and be ready to react to any unexpected issues.