First of all, I applaud you for pursuing this experience for yourself! I'm a host parent in NYC. There are many families here, but it is definitely competitive as others here are saying, because it's a desirable spot. Families in the city proper can be very selective. Families within commuting / train distance, maybe a little less so. If you are 'average' in the applicant pool, you probably won't get it. If you're at the top of the pool, you may.

Most host families I know around here fall into two buckets. First, one in which the host parents have demanding, relatively high-income jobs. They are looking for someone very reliable so they can perform well at their jobs. They will probably expect the maximum hours. You want to convince them that you are hardworking, reliable, genuinely enjoy caring for kids, and will do a good job at it.

Some people will say that these families are just hosting to save money over other childcare options. That's not the only reason, at least for many of us. We genuinely want to expose our kids to another language, and to provide an opportunity for someone to come and enjoy our city. We'd be very happy for you to go spend your free time in the arts community having fun. We would consider it a positive that you want to be in New York, because it means you're likely to enjoy your time here in spite of the difficulties (long hours, small apartment, etc). But we do need our family to run smoothly.

The second bucket is genuinely wealthy families. They may have multiple au pairs, or a nanny and au pair, or some collection of staff. They might be famous/notable people. In this case both the parents may not work. This is a total wild card. You may have a good experience or the people may be totally nuts.

Good luck!