At lower levels your healing output generally out scales damage output. Sic isn't generally good for Faeries in general as when you unlock more of the Fairy skills, you don't want Eos or Selene burning CDs at inappropriate time. A great example would be Eos using Whispering Dawn as soon as someone takes damage--you want to save that for when you need AoE heals.

Selene at 30 however doesn't have access to many skills. I think you only have Silent Dusk & Embrace? I'd put her on Obey and just spam Silent Dusk on mobs that can be silenced. Most notable is the last boss in Sunken Temple--you should try and Silence the Paralyze since Scholars don't get Leeches until the level 40 class quest is complete.