How to earn more coins?

I have close to 30 characters across a bunch of accounts so I'm logging into them every day and taking the free coin. It adds up over time.
The only way you can really farm them right now is by mass leveling up characters. There really isn't any way to farm them quickly and easily.

Although its great to have so many accounts to log in and out, I highly recommend against it if you have a horrible connection or doing this from out of the US.
Nexon likes to Ban IPs.