How do you remember mechanics?

[Maeka]

Most attacks are telegraphed via a system of specific markers that SE has pretty much standardized over Heavensward continuing on into Stormblood.

There's the "Stack on this player!" marker that everybody learns in Final Steps (or we hope you learn lol). There's the "Get away from me now!" marker with little circle around you to denote how far away they should go, the standard AoEs...

Most bosses are pretty straightforward, and those that aren't... you are usually going to be doing these dungeons with Sync'd players, and Sync'd players make it a steamroll unless you get some abnormally derpy groups (I had a group wipe on Leviathan twice in the same duty because the first run, nobody used the Aether Shield and the second, they used it far too early). Most players will be aware of special mechanics (like people having to click the harpoon guns at Bismarck) that they will have it covered.

Unless you're the MT, it's doubtful that your lack of knowing the mechanics will make or break the entire group effort. I'm not saying to go in expecting to leech, I'm merely saying don't be afraid to run content blind. The major exception to this is Thok ast Thok.... please don't go in THERE without at least watching a video to familiarize yourself with Ravana and his cheap attacks.

Most other Trials and Dungeons can be run blind. I ran most of them blind myself, because wiki does not updated when I did my SB MSQ.

EDIT: And also, when you enter, tell people you're new to the instance. In fact, that can sometimes earn you commendations even if you make a few mistakes, if you show yourself to be reasonably competent, sometimes you'll get comms JUST because people enjoy bonuses and WT second chances but most importantly, if there IS something that it is crucial/out of the ordinary that you need to know, usually at least 1 person will mention it.