Correct citing and intellectual honesty is -like most good habits- acquired by practice, reinforced by repetition and improved with feedback.
To know more about how and when to quote, your students can consult the citations webpage which gives an account on how, when, and why to cite sources.
Several resources are available for teachers:
When assigning projects, presentations, dissertations or other deliverables it is important to remind the students the reasons for proper citation. Remember to give examples on the specifics of citing by field (this may vary by journal, discipline and type of source).
For Master projects and PhD thesis, encourage students to start as early as possible to draft a properly written bibliography making the correct citations in the text. It may be useful to give them feedback and point them to the advice and training offered by the library if necessary.