I want to smoke outside of my home
Could you be a little more specific about your smoking?
I'm going to smoke a cigarette in my car privately
You are free to smoke in your car, so long as no one else around you minds. It is also better because then your house won't smell of the smoke.
But it causes cancer. Cancer is bad. I had a few relatives die of it. I know I shouldn't be smoking either but can't seem to stop.
You are correct that smoking is dangerous. Not only for you, but for those who are around you. As such, I'd advise you to make an effort to quit smoking altogether for your own health, but when you do smoke, make sure you do it when no one else is nearby.