Briefly, working as an LNC will depend on your nursing expertise. An attorney will not hire you as an LNC or testifying expert without a strong background in nursing, because that attorney will need to have confidence in your nursing experience and judgment, and that comes only with time.
If you are interested in the work, though, there are many different kinds of legal nursing. Suggest you check out the AALNC, American Association of Legal Nurse Consultants; the AANLCP, American Association of Nurse Life Care Planners; IAFN, the International Association of Forensic Nursing; and CMSA, the Case Management Society of America. Each will give you ideas about preparation, job market, requirements, and certifications.