If anything, Levi teaches you the most when it comes to healing itself and healing while dealing with mechanics. And I'm not going to tell you why either :P (I suggest others not to as well, please)

Identifying mechanics and reaching out for your healing game for certain encounters is part of your job as a healer. I'm practically tossing you into a trial by fire (no, not ifrit), but you'll find self-learning methods more rewarding/practical than copying what others are doing/saying. That is, till you run into real trouble and really have no idea how to handle it.

If you want to test your mettle at one point, solo heal Leviathan EX