First, I would suggest a basic riders course…most schools that offer the course will provide a bike for the training (always better to drop someone elses bike when starting out), and most will allow you to use one of their bikes for the test…they also usually have a few different types of bikes for the class…try them all out, you might find that you don’t like the sporty bikes after riding one for more than 20mins…although the Ninja 250 is more of a standard with farings…
As for new or used, my suggestion is always go used on your first bike…maybe buy one from a dealer, but let someone else take the depreciation and put the first scratch in it…getting a good deal right now shouldn’t be a problem right now being winter and all…and the security issue…well, a 250cc bike isn’t going to be a theifs first target…
Just remember, this is all about having fun…so keep safe (wear the gear and get trained) and the fun will take care of itself…
Later.