A consultant is a person who provides assistance usually to a client. He/she is usually in a position to exert influence over a person, or group. It is essentially about building trusted relationships in which people help one another create value by addressing opportunities and solving problems.
The consultant’s work is defined by his/her expertise (that expertise is based on what a consultant knows and has experienced), the structure in which the consultant works, and the process the consultant uses.
The consultant must be guided by the ethics of consulting. In essence, consultants should always be aware of the cultural and ethical dimensions of consulting.
The consultant must also display integrity, competence, and objectivity.
The consultant should keep client information and records of client engagements
confidential and only use proprietary client information with the client’s permission. The consultant should not take advantage of confidential client information for himself/herself.
A consultant should not provide a competitive advantage to one client through the use of confidential information from another client who is a direct competitor without that competitor’s permission.
Consultants should accept only engagements for which they are qualified by their experience and competence.
In today’s global business environment, hired consultants need to add inter-cultural and new linguistic skills to their consulting toolbox in order to be effective in the business environment.
Consultants must not only be capable but also caring, quick to discern nuanced differences in culture, be meticulous and effective in communication
They also have to be sensitive to how different regions of the world culturally perceive time, work and social order and ensure that their conduct is guided by the principle of integrity. 
Integrity is the cornerstone of professionalism in consulting.
Hope this helps when you need to hire a consultant.
