What is the main reason for getting this bike? Are you anticipating weekends hitting the road, or is this for getting around town or work while the family drives in the van. Be very realistic.
Will this be your first experience or are you an old hand? This is another encouragement to be realistic about your abilities. If it is your first bike, a less expensive used bike might be a good bet to learn on. No need to scrape up costly body work while you learn the fine points of cycling. If you are seasoned, take your pick but understand any new bike takes some getting used to.
It's all about the check book. Unfortunately it's not just the initial purchase that will cost you. As with a car, you need to add in insurance, gas, equipment such as helmet and locks. Realize as well that when the weather turns sullen you will need an alternative means of transportation.
Fits like a glove
Safety requires you to sit on the bike. How is the arm reach? Can you hold the brake all the time and comfortably? How is your access to the clutch...it should be reachable without moving your arms. As for the leg room, you should be able to use your feet to maneuver into parking spaces. This is an issue for shorter legs. If you have longer legs you need to make sure you can grip the tank of the bike while your feet are on the pegs. Motorcycle experts say your foot needs to be able to access the rear brake and lock it. You also need to be able to up and down shift instantly with your toe. If the cycle has a fairing, make sure you can see without any distortion, either through it or over it. All bikes are intended to be adjusted to fit in a limited manner...if anything major is required, look for another bike. There is one out there just for you.
Read up again
Now that you have a ballpark bike in mind, read up on the choices within that category for the bike with the features you want.