Started as a WHM, I used to overheal like absolute crazy and I used to Regen before the tank pulled anything, it wasn't until me and a friend did Cutters Cry for the first time that a friendly couple (playing as a tank/dps respectively) gave me some healing tips, they were very pleasant and we had a laugh, so the lessons stuck.

I used to forget Heavy Thrust...a lot...

I didn't realize you had to face enemies for your shield to proc, I also underestimated just how much damage it mitigated.

Through some good advice and input, I got better.