Hi Smita...yes, you do have to be careful in some places (in bushland or the countryside), but usually only from the late afternoons to around sunrise. If you're driving around in the middle of the day you shouldn't have any problem as kangaroos and most other wildlife aren't so active then. At night they often get dazzled by car headlights and that's when they tragically get run over. Fortunately we've never run over any (we don't drive in the countryside at night very often) and I hope we never do, as I love all animals. If you have to drive at that time, drive very carefully. Unfortunately if a roo jumps out at you, the safest thing is to simply drive straight ahead, even if it means running it over. Many accidents have been caused by people panicking and swerving into oncoming traffic or hitting a tree.
Hi Smita, I have encountered Kangaroos in the wild, and interestingly most often on Phillip Island.
Driving at night along the surf beach roads you can often see a Roo bounce across your path.
I have also seen them while walking. There is a walk to an inland lake on Phillip Island called Swan Lake. The walk takes you along sandy bush tracks and mad made boardwalks. A few times walking along these paths I have encountered kangaroos hiding timidly in the bush. If you are quiet enough you can even score a photo. You'll need to keep your eyes peeled as they are well camouflaged in this environment.
It still amazes me how there is a population on the island. They were never introduced so it means they would have had to hop right across the bridge at San Remo to first get there. (now there's an interesting visual.)