First and foremost, Ontario is absolutely gigantic! Figure out where in the province you want to ride, and what you want to see. If you need some help check out the easy-to-use online trip planner at www.GoRideOntario.com.
Once you decide on where you want to go, it's time to focus on the logistics of the trip.
Licensed to Drive
Be sure you possess a valid motorcycle license from your own country. Reputable rental outfits will allow you to purchase insurance for their vehicles. Secondly, you (and your passenger) are required by law to wear an approved helmet at all times when you are on your bike. Please see the Ontario government's website for specifications.