Just started out on an old Kawi GPZ 750, an '82. I'm only about 5'6 and 160, so you shouldn't have too much trouble on a 750cc bike, and it should last you for a couple years. Respect the power, and as long as you have the strength to pull 750cc bike up if/when you do a low speed screw up and you'll be fine. But yeah, get a piece of crap, don't buy something shiny.