* Use the Romanized spelling: 저스틴 (Jeoseutin) - This is the most common and easily understood way.
* Find a similar-sounding Korean name: There isn't a perfect match, but you could potentially choose a name with a similar sound or feel, depending on the nuance you want to convey. This would be a very subjective choice.
Therefore, 저스틴 (Jeoseutin) is the recommended and practical way to say Justin in Korean.