I am subletting my apartment this summer for june- august utnil I get back to school. What do I have to watch out for?

I go to school in DC but I got an internship in NYC this summer so I'm going to be subletting my apartment for 3 months, my property manager already ok'ed it just said I have to find the sublettor myself.

What should I watch out for? Do I have to write a lease or anything saying that she will take over it? What happens if she doesn't pay rent on time or like causes damage to my things or a part of the apartment? Sorry for all the questions, I'm just nervous but I can't afford to keep this place and spend so much $ living in NYC!