edit: for some reason I tailored this post for rdm macros, even though my rdm is level 1, but you can cater it for any job
Ignoring gear swaps for the moment, if you have less than 20 actions you need to perform there's a fairly simple solution based on what Aerithmay said.
For all your 20 macros, you have them in book 1, and your macro for CTRL+1 could read as follows:
/equip head hat
/equip body coat
/equip hands gloves
/equip legs trousers
/equip feet shoes
/equip main staff
/macro set 2
This will take you to set 2 of the same book, where the macro on CTRL+1 would read:
/equip ear1 earring
/equip ear2 earring
/equip ring1 ring
/equip ring2 ring
/equip waist belt
/equip back cape
/macro set 3
This takes you to set 3 of the same book, and CTRL+1 would read
/equip sub grip
/ma paralyze <t>
/macro set 1
So if you need to para a mob, you hit the same macro 3 times as quick as you can to change all your gear, para the mob and then get back to your standard set. If you are using longer casting spells, you can set it up so the spell starts casting when you hit the macro the first time, then you gear swap the rest of your gear on the next two presses (put any fast cast gear in the first set).
The downside to this is if you think you hit a macro but it doesn't go off, putting you on the wrong set, and the fact that you can't have <st> macros in the first set. The upside is that it's pretty straight forward.
Another way you could set it up, would be to divide it up into different gear builds. So CTRL+1 will equip some enfeebling gear and take you to set 2, CTRL+1 there will equip some more and take you to set 3, and on set 3 you'll have all the enfeebling spells on different macros, with room to switch in the last couple of pieces if needed. CTRL+1 on this set could be nothing but /echo enfeebling set, so you know you're already there. You could use set 1 as a central hub, or you could just use it as one of your gear sets. So CTRL+2 on your enfeebling set (set 3) equips some elemental gear, takes you back to set 2, CTRL+2 there equips some more elemental and takes you back to set 1, and CTRL+2 there just has your first 6 gear swaps and /echo elemental to let you know you're on that set and ready to go. Then all the other macros would be your elemental based spells.
Setting it up like this means that no matter what set you are on, you will have 3 macros (one for each gear build, so if you have more gear builds, you'll have more macros here) that change all your gear and take you to the spells for that gear set, and then you'll have up to about 15 different macros for different spells within that set. Keep in mind that you'll want to have cure III on every macro set, not just on your curing set, and may also want sleep/bind/grav on every macro set if you often need them unexpectedly fast.
For a little more detail, and probably explained a lot better (with pictures!), on how to set-up multi set macros, have a look at
Erecia's SMN Macro guide.