This scene has become a popular one in many colleges, and yes it is quite sickening. I was in the same position as you, moving from an all girls high school to a mixed college; i was afraid my imaan would be effected by the influence around me. . . but Alhamdullilah it made me stronger. When i saw how low the muslims had reached, it made me want to strive more.
I felt i was amongst the very few practicing muslims in my college which made the transition quite difficult and I never considered preaching for various reasons.
By the end of the first year it became quite clear which muslims were worth knowing (coincidently the most intelligent students) and which werent. Still I came to know most of the muslims, i realised that preaching was not always needed because sometimes your own actions are recognised and considered by the people around you and sometimes this is all that is needed for others to wake up and realise what they are doing is wrong. I didnt waste too much time with these kind of people but left them in doubt of their own actions.
My advice to you is to concentrate on your own imaan and find ways to build a connection with Allah in everything that you do. Make your purpose of being at the college clear to yourself and to those around you (you are there simply to study). No one will hassle you.. and you'll find that muslims along with non-muslims will come to respect you, for your intentions and your actions as a sincere muslim. By correctly potraying the image of Islam inshAllah you will be participating in a form of dawa, earning respect and inspiring others.
