I have crossed the 2000 km mark on my bike. With which I have also the confidence to state the above. I did some research in to the reasons and came up with these few most glaring of them.
Ride at constant speed - maintain your speed below 50 kmph.
Don’t accelerate or brake too suddenly.
Try not to use your lights if not required.
Switch off your engine if your stop is longish.
Use speed/xtra-premium.
For a more detailed explanation, you could see the following.
https://facelessind.blogspot.com/2006/10/pulsar-180-does-50kmpl.html
Over all I am in love with my bike and would recommend it to all kinds of people - the conservative to the rash driver. I tend to sway between both extremes, and have found myself riding with a lot of confidence in both the cases. As opposed to apache, which I did ride for a week (borrowed from a friend)
Regards