The go-to advice is watch what other people are doing and if they have no hesitation in doing it, they're probably doing the right things. Pay attention to what alliance you're in as someone will probably put down markers for some of the fights and you'll need to go there at some point during a fight if they've been placed down. (A, B and C respectively. You can check what alliance you're in at the top of the party list.) If your party zooms over to the alliance marker all of a sudden you'll
There's basically two ways they design fights in general in FFXIV, you fail a mechanic and repeated failures of that mechanic will eventually kill you, or you fail the mechanic and it kills you immediately. So, if you mess something up, don't feel bad about it, failure is the key to success, try and figure out what killed you so you can look out for it the next time. Most of the casual content (dungeons, normal 8 man raids, 24 mans) are designed with the former in mind but some fights have the latter in mind.