Biggest piece of advice i try to give new people is to ask for help when they need it(dont be afraid to say you dont know something - we all had to learn at some point), and not get stressed out about the things they dont understand yet. This game like every MMO is huge, complex, and can be hugely complex if you let it.
Yeah, some classes are much easier to learn basic sequencing on then others. Black Mage is literally a 4 button class for a long stretch of levels(fire 1 for damage, transpose to stance switch, blizzard 1 for mana regen, thunder 1 for extra DoT damage - sequence is essentially Th F F F F Tr B Th B Tr F F F F for almost 30 levels and switching from single target to AoE only even means swapping F2 for F1), and you slowly start adding/changing some of those in the later stages until everything shifts radically at level 58-60. My understanding of monk is secondhand and limited, so i wont say anything class-specific thats likely to be wrong and confusing. But one piece of advice i can give that is more universal - if you arent feeling comfortable with your rotation you can always practice. Easiest way is to get to know a striking dummy for a little while. Many FCs/people have level 50 or 60 ones in their yards. You cant "kill" them(their hp bar just refills when depleted), so you can practice going through the moves as long as you want until youve got a good feel for them. They dont really simulate positionals well, and a real fight usually has some mechanics to worry about, but if you have the moves down youre well on your way. Then like Teiren said knowing the fight is key. Between knowing your moves and the fight mechanics, youve got 95%(roughly) of the toolbox, THATS when the theorycrafting(openers, cooldown management, etc) becomes relevant if you need to be the absolute best.
Anyway, if my rambling barely coherent thoughts have been at all helpful then im glad to have shared them. Continue having fun, and never be afraid to ask questions.