Some things to be aware of with the macros in this game (which are honestly not that great).
First, the text command glossary, so you know where to look for specifics.
Second, macros can make things easier, yes, but I'd highly recommend not using them for combos. In order to do that, for pretty much every class, you have to put /waits or <waits> (same thing, different syntax) in between each skill, and the macro system only handles whole seconds. (Either syntax will accept decimals, but /wait rounds them and <wait> truncates them.) With a base GCD of 2.5 seconds (lowered by skill/spell speed), that means the best you can do with macros is a 3-second wait, so you're building lowered DPS into those combos if you use macros. You also end up screwing yourself via inflexibility; Fire a macro, boss goes invulnerable, your macro keeps going, trying the next two skills, which is a waste.
Third, you can only ever have one macro running at a time. If you fire one macro, and it has a /wait in it, and you fire a second macro of any kind during that wait, your first macro is stopped wherever it is. It's even possible for a macro to interrupt itself, even without /waits, if you're spamming it enough and latency and circumstance align correctly; this is usually not a problem, but if it's really important to use CDs in a certain order, the CD-stacking type macro I post below can be problematic.
All that being said, there are a few common uses for macros outside of using them for combos.
One is communication, telling your party when you've used an important CD. The usefulness of this varies; if you're using a stun just for extra DPS on a boss where no one cares about stuns, it can get annoying seeing it pop up in chat every single time; but if you're part of a stun rotation, it's more important
/micon "Blunt Arrow"
/ac "Blunt Arrow" <t>
/p Just used Blunt Arrow on <t>!
Another is stacking all your off-GCD damage/defense buffs on one button. The way these work is that it will use the first ability that's available each time you press it. So if you use all your buffs at once, you can just spam the button until they're all up. If you use them one at a time, in between GCD moves, you hit it in between GCD moves until you see one buff pop up, then move on, and so on. The big disadvantages here are that you can't choose a specific buff at a specific time, and you can only see the icon for one of them, so you need somewhere else to track the other CDs. (Rearrange these in whatever priority order you want.)
/micon "Raging Strikes"
/ac "Raging Strikes"
/ac "Blood For Blood"
/ac "Internal Release"
/ac "Hawk's Eye"
Another that's ARC/BRD specific that a lot of people do is for getting lazy about Misery's End and Bloodletter. It's another spam-until-it-goes button, where it uses Misery's End if it's availble, Bloodletter if it's available, then the off-GCD move in question.
/micon "Heavy Shot"
/ac "Misery's End" <t>
/ac "Bloodletter" <t>
/ac "Heavy Shot" <t>
The idea is to do this for every one of your GCD attacks, so that whatever GCD attack you're using, you'll spam it and ME/BL will fire first. Be aware that if you can reliably hit those two skills on their own, this is a DPS loss vs. just doing it yourself. First, because you'll run into situations where both ME and BL are available, and the macro will make you use ME > BL > Heavy Shot, where the optimal use is ME > Heavy Shot > BL. Second, because macros can not queue the way raw abilities can. You can hit a raw ability from the spellbook around half a second early, at it will queue up and go off right on time. Macros can't do that, so you have to spam the button to get it to activate as close to the CD as possible, and it'll always be <your latency> late. This isn't nearly as bad a DPS loss as macroing combos on other classes, though.
If you want more specific suggestions, I'd say just google for "FFXIV <insert job here> macros" and see what other people are doing. Just be aware of the limitations of the system and what you're trading off for any convenience/ease you end up with.