I would start by buying a used board. Get something inexpensive and spend the first month or so on it, until you have a feel for what works for you. The first month of surfing, you're going to thrash whatever stick you have. Might as well thrash a $100 board, instead of banging up a $500 one. New longboards are REALLY pricey, and I think it'll hinder your learning curve if you're out there worrying about damaging the new board. Start out with a medium-sized long board, probably 8' to 9'. Then once you feel "comfortable" on it (maybe a month), move on to picking out something nice. I'm partial to Hobie, myself.