Vaseline + Styrofoam = Napalm.
Basically, what you do is get a piece of cloth around 40cm by 40cm. Get a nice ball of Vaseline, around the size of a tennis ball and place that in the centre of the cloth. Begin placing pieces of Styrofoam around the ball. Once you've got a ball of Vaseline with Styrofoam stuck to it, wrap the cloth around it.
Light, throw, profit.