If you want, you can include the leveling path I posted in the "How fast is fast?" thread, though I think something better to touch on is Good mob selection for leveling. As while at lower levels this is not as significant, later on it starts having a more noticeable impact.

Like for someone soloing on DRG, if going as /mage, want to try and avoid mobs that Silence, AoE Sleeps, or Amnesia often, or have TP moves with high Damage potential like Sickle Slash and Death Scissors to name a couple. This changes a bit once get access to the JA trigger for Healing Breath.

Mages in general its good to focus on enemies like Beetles and Crabs due to them having MP to Aspir. Worms make another great target for mages if have access to Silence as well due to them not being able to move once engaged.

Fat bats in general make good targets due to not having many dangerous TP moves.

Also don't forget to keep in mind enemy weaknesses and resistances to damage types.

Just a light sampling of some things that go into selecting a good target mob.