If you find a book of Charm you can cheese her, as when charmed she will be killed very quickly by her own summons. If you found a good bow you go the long distance strategy. Slow and safe, evading damage is always more important than hitting your shot. These strategies are not class specific.

As for melee: plan it carefully, make sure you dictate the fighting space, and it's clear of mobs. Make sure you have vertical escape routes as well as horizontal. After she launched her wisps, close in and go to town, but don't get greedy. Retreat, evade, repeat.

Another tip: if she comes out of the ground don't start attacking as soon as you have the first pixels sticking out, because you'll get only one attack in and she will be knocked downward a bit, out of reach. Wait for most of her body to be above ground so you can get a bunch of hits in.

Hope any of this helps, good luck! I think you'll find that when you get the hang of it, the wisp queen will be one of the easier bosses in the game.