Here's what I do (don't do it if you collect cards): after you have the ragnarok teach diablos enc-none. If you haven't already, teach your GFs all of the refining abilities you can (especially card refinery, which requires Card). Refine Odins card into dead spirits and refine those into deaths. refine one of the brother's card (can't remember which) into dinobones and turn those into quakes.

Junction Encounter None and go to the Island Closest to Heaven/Hell. There are tons of drawpoints that fill up quickly (if you go to another island then by time you are done the other should be filled). Really good ones like flare, meteor, and even Ultima!!! Once you have 100 ultimas for at least three party members (it may require some patience, also you can refine ultima stones given to you by defeating ultima weapon) junction them all to elemental defense and you'll be immune to all elements!!!

Other good tips for junctioning: Aura is excellent for Strength. when fighting marlboros, defend yourself against berserk and confuse or you definately die. and...that's it.