To avoid suspicion of plagiarism you must always cite your sources. If you copy text into your work you must also use quotation marks around the text quoted. In this guide you can also learn some about citing - that is how to use others’ texts in a correct way.
One piece of advice is never to use the work of a previous student, or of a current fellow student, as a model or inspiration when you write your project, since there is a great risk of you plagiarising. On the other hand, using sources from an essay or thesis, searching for them, reading and referring to them is a better way.
Avoiding plagiarising is a matter of training your ability to write independently. At Mälardalen University support for academic writing is available to you as a student. Reading academic texts involves you training your ability to write academically as well. See how citations are made in an academic article within your subject.
A lot of students who have been brought up before the Disciplinary Board have said that study stress has led to them not checking their text sufficiently well. Plan your time. Read through the assignment properly and make sure that you understand what you are to do. Ask your teacher if you are the slightest bit uncertain. Mälardalen University offers support during your studies concerning study technique, among other things.