What's the best "first motorcycle" to get?

Depends on where you live. My advice: get one that’s used. Learning the proper care of a motorcycle is best applied to a bike that is 5 or more years old. That way, you won’t curse the day you bought it when it becomes scratched by dropping it, or forgetting to remove the disk-lock on the brakes.

My first bike was a Yamaha 500 special from 1984, purchased in 2002. It’s previous owner was a man who lost an arm in a farm accident.

Definitely go with a used bike. Not only for the reasons that VoodooLogic mentions, but also because you’re almost assured of finding a better deal. There’s always some dude getting married or having a baby or in some other way being forced to rid himself of that one last vestige of his youth. That’s where you step in to get a nice, cheap bike.

But to answer your question—what kind of bike are you interested in? Sport bike? Cruiser? Touring? What kind of riding are you going to do? Long-distance, or in-town commuting? Do you want to go fast, or save on gas (in which case your best bet would be to stick with the Vespa)?

Most importantly, you’ve got to be honest with yourself about how much bike you can handle. Your life truly depends on how honestly you answer that question. Motorcycles are inherently dangerous. Getting on one that is too big/heavy/fast will kill you.

I live in London, UK and I’ll be using a bike for riding to work and occasionally for tripping to the country. I’m thinking about honda cb500 (I’ve read It’s good as a first bike) but I’m still not quite sure about it.

My first Bike was a Bridgestone 70cc. It topped out at 40MPH but then I lived in the city so it worked great. I could run for a month on a tank of gas going to work and back. It was transportation and that was all I needed. I went to bigger and better as the money came BUT that old Bridgestone was one of the best