How to get the most mileage out of my Hunter 350?

I recently got a Hunter 350 from my friend to daily drive it to work, it's about a 20km round trip. Can you guys help me out with how should I drive it or what can I do to get the most mileage out of it? What should be the speed range for each gear to get the most mileage or something like that? I'm pretty new to driving a bike for efficiency so please don't mind my ignorance.