ANSWER:

A doctor is permitted to look at awrah only for a legitimate reason and at a specific place.

Likewise, a man who wants to marry a woman, he proposes and he looks at her in the interview. Further looking is transgression and must not be done. 

I think presented my question wrongly. I am very aware of Surah 24:30.But I am confused that you said one can only look at a girl at the initial meeting. I thought if one is quite sure that the marriage will go through, one can look at the girl to make him go ahead based on the hadith of Jabir ibn Abdillah and others.Did is misunderstand the ahadith or what is the evidence that I am wrong?