:sl:
1. pamphlets are a good idea. if you do this, as well as including ayahs and hadiths, try include, explain and focus on the whole uni lifestyle as well and its negative affects. these things tend to go hand in hand i find. you have an intermingling environment, then its only a stones throw away before you have people intermingling.
2. try getting a sister to advice them. for example if your own sister attends the uni then ask her to speak to them.
3. avoid talking to them personally because if you do that then they will deem that inconsistent on your part and are not likely to take heed.
4. start a website (or something along those lines) addressing the issues...thats another good indirect way.
The sisters seem to mix with the guys more then the brothers do with the girls.
sorry, but this doesn't make sense. if the sisters are intermingling, then there is someone that they have to be intermingling with. unless you mean the kuffar men?
If the sister was wearing hijab then she no doubt knows its haram.
that's actually not always the case.