2. How much bike can you honestly handle?
While you're still learning to operate a motorcycle well, it's important to not be hindered by a bike that is too big, too heavy, or too powerful. Knowing what you can manage not just physically, but mentally, is very important. Ensuring you can place both feet firmly on the ground and reach the controls is a good start, but also think about how good your hand-eye coordination is. If you buy a bike that is powerful and fast, do you have the discipline to refrain from doing stupid, stupid things with that power?
3. How much money do you really want to spend on your first bike?
"Dropping" a motorcycle when you are new to riding is a reality. Damage to a bike means having to fix it, which costs money, and smaller, less expensive bikes are easier and cheaper to fix compared to their larger counterparts. Also, larger engines typically mean higher insurance payments for the first three years you have your license.