>>Get rid of potions/mats. These often sell poorly (for too little gil, too infrequently). If the sale history shows less than 1-2 sales per day then it's vendor trash.

>>Throw away combat gear under Lv60. Palace of the Dead is the best way to level a class from 1-60 and requires zero gear.

>>Keep sparse sets above Lv60. A set for each job type for every 2-3 levels is OK and will leave you with upwards of 16 items in each armory tab.

>>If the materia isn't VI for your class, sell/pitch it. End-game content (4.0-4.1) is VERY doable without it. You can stack up on Cracked Clusters (trades in for VI stuff) instead if you like.

>>Consider pitching the music scrolls. Many require Master Crafting Books up to ALC Lv60 (read: HIGH minimum stat requirements to craft). If you're not impassioned by all crafting classes then don't worry about the scrolls.

Glamour and Music Scrolls are up to you, but hopefully this helps you cut down on some stuff!