There is a strong need for qualified interpreters with credentials as we are currently experiencing a period in the interpreting field where supply is not keeping up with demand. The greatest demand for interpreters is in medium-to-large cities. The more mobile you are, the more likely you are to find an interpreting job.
Interpreters typically fall in one of three categories
Agency interpreter, meaning that you are employed by an agency that provides you job assignments.
Free-lance interpreter, meaning that you are responsible for finding and maintaining your own client base.
Contracted interpreter, meaning that you take on aspects of both the agency interpreter and the freelance interpreter. You provide services to an interpreter services agency or to other agencies in accordance with the terms and conditions of a particular contract or contracts. You are not an employee of the interpreter services agency or any other agencies for which they provide services. 
1. About Interpreting Education Programs. (n.d.). Retrieved December, 2017, from https://www.rid.org/about-rid/about-interpreting/become-an-interpreter/