Self-plagiarism is taken seriously throughout the academic community. If you would like to quote yourself, simply cite yourself as you would any other source. The University of Arizona created a tool to detect self-plagiarism, explaining:

It is our belief that self-plagiarism is detrimental to scientific progress and bad for our academic community. Flooding conferences and journals with near-identical papers makes searching for information relevant to a particular topic harder than it has to be. It also rewards those authors who are able to break down their results into overlapping least-publishable-units over those who publish each result only once. Finally, whenever a self-plagiarized paper is allowed to be published, another, more deserving paper, is not.

You might argue, as a student, that this does not apply to you because you are not seeking publication. However, at DePaul, we strive to uphold high academic standards worthy of entering the conversation at the professional level. You can also think of it in terms of earning two grades for one work – this is simply unethical.

So, while you can cite yourself, you should do so in the same way you would any other researcher. Using quotations of evidence for your argument, and make sure your overall argument is striving to contribute new information to the field.