Yeah, don't worry about it. In the early dungeons, you definitely feel a bit gimped as a pally, but once that super kind healer told me to shield lob on pull, flashx3, I've almost never had a problem. You can place markers on your bar (I do 1 & 2 and have them key bound alt-1, alt-2) if you want to be pro-status (i.e. save yourself headaches.... if they ignore markers, it is on them!). You may be a bit rough around the edges at first, but you'll be fine in no time
If you're really finding yourself unsure of things, you can google "ffxiv enmity ui youtube" and "ffxiv customize ui youtube" and watch some vids and you'll do just fine!