Financial Analyst--Consulting

Does anyone do financial analyst consulting or working as a contractor to companies as a financial analyst?  I would like to start doing this as a business, however, I do not know how to start.  How much do you charge, how do you market the business, how do you set your fees, etc.  I would like to do temporary work part or full-time for companies on an on-call basis, hopefully working many of the hours from home, but would prefer to market and invoice directly, myself without going through a temp agency.  I would see the benefit to the company as having a consistent on-call employee without having to hire new staff and being able to onload and offload their payroll easily and quickly, ramping up hours for projects or down when the project is complete.  For me the benefit is flexible scheduling, working in multiple environments and quickly learning many new industries and areas.  Any advice on doing this?