Healing doesn't really have a rotation of spells to go through like a DPS spec does, however, there are often certain types of situations that arise where you can respond in a certain fashion. I've detailed some of the most common situations below, as well as how to heal them. In the heat of battle, you may not always be able to stick to these things exactly, but with a little practice they should become second nature.
If you have any questions or feedback, you can leave a comment below or contact me on Twitter @PrestonDvorak.
April 21, 2017 - Made a very small update to the Grid saved variables on the addon page.
April 16, 2017 - Moved Aman'thul's Wisdom up the legendary BiS list. It's performing very well in real-life logs. Updated Grid saved variable file on downloads page.
April 6, 2017 - Fixed BiS trinkets for large-group healing being out of order on the page and in the spreadsheet.
March 31, 2017 - Completed the full 7.2 gear and simulation overhaul for best in slot lists, trinket rankings, etc.
March 26, 2017 - Updated Talents and Builds page with new talent system that supports displaying multiple builds. Added information for Raiding and Dungeon/M+ builds.
March 23, 2017 - Reviewed and updated guide for 7.2, including new artifact traits and minor talent updates.
March 20, 2017 - Added initial addons page with Grid and WeakAuras overviews.
March 17, 2017 - Updated legendary item list with simulation data.
February 21, 2017 - Did a full review and update of all trinket ranking information.
February 12, 2017 - Added Perfectly Preserved Cake to BiS trinket list, below Etraeus' trinket and the legendary trinket.