For skills below 75, just follow the old skill up guides. For skills above 75, go for worms in Abyssea La Theine or Abyssea Uleguerand. Besieged works up to at least lvl 80.
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Lyonheart of Lakshmi lvl 99 NIN WAR BST THF BLM SCH WHM Cooking 100.0+3+3
For 80+, macro all your Tier 1 spells, set /RDM or /WHM and Barstone, go pick on a worm in La Theine and spam the T1s. Your goal isn't to kill the worm, or get exp, it's to get as many casts on the thing in as short a time as possible. T1s cast the fastest, have the quickest recast, and you will get far many more for your MP pool - which means far many more chances to get those .1~5 skill ups!
There are also new worms in Aydeewa Subterrane that are 87ish and can be used to cap. Useful if you want to skill up casually without burning up stone time. I just cast spell and move out of range when it retaliated ad nauseum.
I don't remember which entrance I zoned in from but I do remember I was able to get close to capping enfeebling before having to leave to do an event.