First off, find a place near you that does the MSF basic rider course. It's the easiest but most informative way to get your M license (may vary by state). Bikes are provided, most likely some little 125 or 250 that weighs less than you and at the end of the course you have a full license. I don't recommend starting out on a sports bike. 600's are quick enough to easily kill inexperienced riders who start to feel too comfortable too quick, and something like a 250 Katana won't keep you interested for six months. Now, this is just my personal opinion, but I would never pay too much for a first bike either. Lower displacement (think under 700cc) 80's and 90's cruisers are a dime a dozen and if they're in decent shape then they make great first bikes. They're not heavy like a Harley, not too powerful for beginners, and not something to cry over if you happen to lay it down. Only problem with going too old for a bike is that you have to order any and all parts you may eventually need online or find someone who's parting out a similar bike on Craigslist or something. Man, I'm getting lazy about catching typos...