Well here's what I did. Maxed every 2nd job skill except Blood Drain and Booster. For myself I chose 17 Booster and 6 Blood Drain seeing as they have almost equal durations and the 2% gain from 6 Blood instead of the 1% gain from 3 Blood is very very noticeable. Saves me lots of HP pots.
Blue Aura maxed is important since it allows the use of Advanced Blue Aura which can save the life of an endgame Battle Mage at bosses more than once.
Don't sacrifice Yellow Aura for Dark Aura until you have Advanced Dark since actually in some cases with slow staves, Yellow will benefit you more. I'm pretty sure Body Boost at max might make Dark better but I don't know yet. If you want to keep Dark then get a really good Evil Wings since it's speed is Fast(4) and booster with that is plenty of speed. Use dark with it and you are set.