How to screen grad students?

[Jonathan Reizovic]

 Hi

I have a property that I am prepared to start renting. I read the step by step sticky about screening and prequalifying and it seemed to be pretty straight forward, that is until I got a bunch of college students responding to my rent ad on Craigslist. I have mostly received emails from grad students, which I'm guessing is much better than undergrads, but I live in New York where it seems you can get stuck with bad tenants for awhile if they don't pay. 

My question is how do I screen these tenants? I assume most will not be grossing 3x the rent if they are still in school. It seems most want  live with 2 roomates (as it's a 3 bedroom rental). So should I require that each grosses at least 1 months rent? Should I have parents cosign?

Thanks in advance.