Luk Mage?

First get at least 80 int. If you don't you'll have to rely on mercenaries to kill everything. After int, start putting points into luk. 

Try to aim for gears with +int and not +int% 
For starters, try getting metal wings(from magic marionette or blacksmith)
For armor Mage Robe and Mage Hat are ok. I still have them on my lvl 90 luk mage cuz I'm saving for a good md (so expensive)
For your special use the mq special until you can get the ring from the Owls in land under cultivation.

Also to level, do your main quest until you get to level 70. Get storm, max it. Also, put 5 points only into arrows, wall, lance, javelin, and blast. Get impact to level 7, and max mp charge. Maxed quick draw wouldn't hurt, but takes some skill points. You can farm b nuts until lvl 80 but it'll be pretty slow, for combo use impact>storm>mp charge(swift)((I don't think swift even affects it)). Also set targeting to far. 

It might be a little hard, but I'd suggest maxing your luk Mage first before all your other characters, by farming nightmare crystals. More levels=More stat points-->more luk=faster nc farm=faster leveling. For your extra skill points, feel free to invest in refining and more matk from battle skills to help one shot nightmare roars.