For actual combat, macros generally should not be used, with only a few niche exceptions. They can be handy for things like automatically setting pet skills to your hotbars when summoning different pets, changing a Warrior's skills depending on which stance you're in, and so on. Or just using them as text popups with sounds effects to alert people to mechanics in certain fights.

The thing with macroing weaponskills and spells is that macros don't queue like regular skills do, which means that there's always a longer delay when pressing a macro compared to just pressing a skill. You also can't make them wait less than whole seconds, and since a GCD is 2.4-2.5 seconds, you're automatically losing at least half a second if you try to macro several skills together.