Before beginning an answer, it is important that you plan it properly so that it is crafted and structured to suit the question. You must also refer to the examiner's assessment objectives to ensure you have met the criteria.
Below is a structure that you could use for your answer.
Consider these example answers based around Hyde's brutal attack on Carew.
Stevenson describes Mr Hyde to be evil when he murders Carew. This is an evil act because murder is a really bad thing and the religious Victorians will have known this and would have thought Hyde was a bad man for breaking the Ten Commandments. The murder is described as vicious and brutal. An example of this is 'clubbed him to the earth.' This is really bad and makes me scared of Mr Hyde because he is a bad man.
Stevenson presents Mr Hyde as an evil, ugly criminal who commits horrific acts and doesn't repent his ways or accept any responsibility for them. In the passage above, Hyde is brutally attacking a vulnerable, respectable old man, Carew. This results in his death, which would have shocked the Victorian audience as to murder a fellow human being meant breaking the Ten Commandments - something that a religious Victorian readership would have thought was unchristianly and evil. Thus, Stevenson presents Hyde as a brutal murderer to the Victorian audience. 'Mr Hyde broke out of all bounds, and clubbed him to the earth.' The use of the verb 'clubbed' indicates how brutal Mr Hyde was and the imagery presented to the reader is horrifying and vicious, indicating the true nature of Hyde's unforgiving nature.
Using the skills you have learned and revised, try to answer the Dr Jekyll and Mr Hyde question. Time yourself and make sure you are meeting the examiner's assessment objectives.