You should be able to charge $100/hr for your services as a software consultant.

My advice would be to plan to spend 15 hours a month (5 hours of research on consulting practices, 5 hours of actively pursuing leads, and 5 hours of billable work) on this. Over time you should be able to ratchet down everything but the billable work.

Patio11, in particular, has written quite a bit about this sort of thing. I highly recommend checking these articles out:

http://www.kalzumeus.com/2011/10/28/dont-call-yourself-a-pro... http://www.kalzumeus.com/2012/09/17/ramit-sethi-and-patrick-...