On BLM/RDM, you can get 6 MP/tick in Refresh for when you idle. Owleyes / Refresh Hairpin / BLM+2 body / Serpentes set / Stearc Subligar. You can even get another one from the WoTG earring, making 7. Combine that with /RDM's refresh and that totals 10mp/tick outside of Abyssea.

Don't forget that you could also be /healing in between nukes if you have to wait more than 20 seconds. Also, yeah, Aspir and Aspir II when they're applicable, as well as Convert. You shouldn't be having too many MP issues outside of Abyssea.