One tip for Cover is to put it in a macro. Mine looks like this:

/macroicon "Cover"
/ac "Cover" <t>
/ac "Cover" <tt>
/wait
/p Casting COVER - Stay close to Sapphidia!

This will cast cover on your target if you have a player selected. If you have a mob selected though it will instead cast Cover on whatever the mob is targeting, which means you can instantly press it if the boss you tank swaps target without needing to retarget the player it's swapped to, or simply tab target to one of Livia's adds and hit it.

The /wait command ensures the message in party will only happen one second after you release the key, so you can Spam the button until Cover pops up without worrying about 400 messages, as each button press resets the 1 second wait.