Plagiarism is the act of copying one's work and making it your own.  Plagiarism in HiH will give you an extremely low grade.  The best way to prevent this is a plagiarism checker.  There are plenty online to use.   All that needs to be done is a simple copy and paste, pressing the check plagiarism button afterwards.  If the work is not published, there are several options to prevent plagiarism from another student:

1. Use complex and compound sentences that are tough to copy- Create a sentence which will be hard to mirror.  This can be used by jumbling many words and different punctuation together.

Ex) The potency of a potion can range from weak to strong; however, many think that mild effects do not exist.

2. Using words no one ever uses- For example, use the word zazzera when describing hair or hippopotoquippedmonstrosisdaliophobia when describing the fear of long words.  It is important to note exactly what the word means and its connotations before using it in writing.

3.  Look up different sentence structures and words- Mix up your writing a little, whether it is in tone or the way your sentence is shaped.  There is no shame looking up what a word means in the dictionary or an alternative word in the thesaurus.