What should be done first before commencing treatment on a conscious adult?

If the patient is conscious and in a stable mental state in which they can knowledgable answer a serious question without conflict then you must ask them for their consent before begining any type of treatment, the only exception is emergency treatment for a patient who is unconscious or does not have the mental capacity to answer a question like that at that time, in which case a relative is contacted, if there is reasonable time available