There are many ways to earn EC, let me name a few.
-Run Phoenix Valley
-Do the quest chain in Frost(although it is more for getting Pure God Stones, it still gives EC nonetheless)
-Get a squad together and do GV
-Do your BHs
-The treasure quest from Sharp Spear gives EC I think, I just never got any yet.
-If you are a good artist, you can take commissions for EC.
-Go to Rancor events and kill the mobs. You can get a lot of EC just by picking up what other people left behind. They can't QQ over it because if they wanted they should have picked it up. It doesn't count as stealing from them if they didn't bother to pick it up.
-Do the Celestial Tigers event. The Head Hunter has a quest that goes with the event, get it. Rack up 2k+ contribution and at the end of the event you will have five minutes to get your prize from a mailbox. The prize contains a Desperate Horn which is turned in with the Head Hunter for the quest you got before(or during) the event. You will also receive some packs. I don't know what is in the packs for the top ranking people but the normal packs everyone with 2k+ contribution gets contains EC.
Sorry for the long post but I wanted to be as helpful as I could.
