When I was leveling my crafts I basically just spammed the same leve over and over again. There's usually a particular leve that grants a lot more Xp than the others, and was generally cheaper to craft. Turn in an HQ item and get crazy Xp.
It's probably the most cost efficient way to go since you have limited leve allowances. Also, definitely level up your MIN and BOT, in the long run it will save you millions