Look for an art supply store. I remember Utretch had one or two in Manhattan. They will have staff who can point you to the right medium/paint/brush combo. If you have a valid student id (ccny, cuny, community college) you'll get a discount. I'd start with acrylics or oils before watercolors. I heard watercolors are harder to manage when you are starting out. you can take a learning annex course to get the basics down - and meet chicks there, too.