To extend on this, you should separate yourself from the routine customer service as much as possible. Automate the first tier with extensive FAQs, screencasts and self-help resources. Train up a good outsource worker to respond to first- and second-tier support requests, elevating to you only when it is outside of their capabilities.

This is something that Rob Walling talks about extensively. He personally deals with customer support for the first several months of his app, so he can understand the pain points and what needs to be added to self-help resources. Then he writes up an extensive training manual for outsourced workers and begins to train them.

Eventually, he stops dealing with "OMG I lost my password and don't know where the reset is?!" questions...and only deals with customer support that is actually worth his time.