I started on an '82 Suzuki GN 250, a small UJM that was ratty looking but ran. I traded a mountain bike for it, plus a 100 bucks cash. I spent an afternoon learning how to ride it, then proceeded to spend the next couple months taking it apart every weekend and going through it as much as I was able to. I repainted the tank and side-covers, polished off as much rust as possible, and really turned it around into a nice, clean, used motorcycle. I never dropped it, or crashed it (I was saving up for larger and more expensive motorcycles to do that with), and eventually I stepped up to a Suzuki Savage, a 650 single. Man, that thing felt like it had a ton of horsepower on it the first time I roared onto the freeway with it. I ended up taking the MSF course about two years later, to knock down the insurance costs on my 750 (V4 baby!), and while it might not have been the best, newbie friendly, way to start off on bikes, I'm glad I did it, and I would do it all over again. No matter what I'm riding, I think about different bikes all the time, and when you're just starting off, I think it best to learn how to be as defensive as you can. An underpowered and slow machine can really give you time to think about what's going on around you, and how you're going to avoid all kinds of stuff coming at you from every direction. Ninja 250? Good. 500? Good.
It doesn't matter what your style is, because at the end of the ride, you want to make sure you're going to get there in one piece. If you buy a POS, you're probably going to worry about being stranded somewhere, at some point, and if you get something just a little nicer, that might happen, too. I think you should get the best thing you can afford in your budget, which is probably a well maintained 250, of any ilk, and when you're confortable and confident in your abilities you'll find the next bike. It's always about the next bike. You'll never be 100% satisfied with what you've got, and if you are, say hello to Elvis for me.
