If you plan to submit to most NY publishers, you need an agent. Unless you meet an editor at a conference and they ask you to send them something of course.
So, in order to give your work the best chance of acceptance you must do your research. You must study each agent's guidelines to determine if you should be submitting to them along with just what they want to get from you.
Not sure where to find an agent? Try AgentQuery. It's the largest internet database of agents so you have plenty to choose from.
Here's some good agent blogs to start with.
Jessica Faust & Kim Lionetti
Order listed has no significance:-) And if you haven't checked out Miss Snark, you need to. The blog isn't active any longer but the archives are stuffed full of information.
And don't forget to check each potential agent out with AAR. (Association of Author's Representatives.)