If you're playing solo with a mage, first off: Don't grind - do levequests instead. If you've completed your 8 leves for the day, well, you're around the level in an MMO that grinding on your own will probably yield pretty poor results. Having said that, in the next patch you'll be able to 'stack up' on leves and do 99 in a single day if you really want to, so perhaps it will suit you a bit better. But definitely leves for grinding.

Mages aren't exactly the ideal thing to solo with, though. They die way too easy to take significant hits for a long period and most enemies have a long range attack so you can't rely on that, either. Danielle never really solos her mage, she'll always look for someone to level with - usually me.