Greetings to all.....I am, for all intensive purposes a "newbie"

. Slowly but surely the desire has been building to start riding. I've had my eye on the M50 black, but I do not want it to be my first bike. I have thought of getting a practice bike first, but which one or does it matter?
Since I have never ridden a bike I thought it would be a good idea.
Any suggestions for getting a decent used bike?