You as a layman
May never experience this
And it is most likely
You won't
But
If you ever catch on fire
Remember the three rules I speak of now
1.stop
          Don't panic, realize your situation, and that you can be okay though calm, concerted effort, don't run! Running only creates oxygen to fuel the flame
2.drop
         Fall to the floor, even the very act of being on the floor smothers whatever part of you that is burning that hits the floor. And it is necessary to be on the floor to achieve the most important lesson being taught within my words
3.telephone
          Now that you are on the floor, pull out your telephone. Strike a pose, and take a selfie. Because for gods sake you are on fire, and you know that it can go viral. And really, dying by burning to death is worth it if you are able to entertain someone in doing so. Instagram will go crazy over you

And I suppose step four would be after you have a picture you like, then  roll to put the fire out. But most people never make it this far.