For help about gearing choices or trinket selection, you want Questionably Epic Live, a healer simulation tool made by Voulk that will take care of all the complicated math for you and present you with your best option from what you have avaliable, and also there is a Wowhead guide on how to use the tool properly.

If you have any question regarding your specific situation or would like help reviewing your logs, you can always ask for help in the Evoker Discord, as most of the people that write the guides on the spec are active in there and there is always high level players ready to give a hand.

All of the information you will find here is in some way or another put together from all the resources avaliable about preservation. And huge thanks to all the people that put in the work so this resources are avaliable to everyone and the staff at Wyrmrest Temple.