The scholarship essay is not too dissimilar from the personal essay/statement. The requirement in this essay is to add to information provided on your application form with more useful facts about you as an individual which will assist the assessment and decision on an application.
You should start the planning of the essay by writing down everything you can think of about your hobbies, interests, sporting achievements etc. then order them so as to provide a true image of yourself and how you would fit in to the job or course vacancy.
It is useful to see the scholarship essay as a good chance to persuade the reader to lean towards favouring you as to your suitability. It is far less of a strain than the interview process so should be treated as an opportunity to be tactfully pushy and to put across your case in a favourable light.