This is copied from the Warhammer Online Herald owned by Mythic/EA from a grab bag question. It gives a clearer picture as to how the guild levels.

Q. Do things outside of normal experience gain contribute to our guild levels, such as achievements through Tome unlocks (although I'd assume those would be personal achievements)? Or renown ranks (I'm assuming those also contribute to guild levels)?

A. In last week’s Grab Bag, I mistakenly stated that guilds will get experience from anything that a player gets it from. This was incorrect. Experience contributions come only from killing creatures and killing other players. So, things like tome unlocks and quest completions do not contribute to guild experience. I’m very sorry for the confusion, and have edited the original reply to reflect this.

We are currently recruiting for all members of Destruction!!! If you are interested, please send an in game tell to Alkitha or Nathalie. We will hook you up.