Hit it around the edges, like taking a chord from the edge of a circle, and try to use the top half of the bit to do cutting. Good ax technique depends on accuracy, on top of which you can slowly add strength as your accuracy improves. If there's a crack in the end of a round, you should be able to put the bit of the ax directly into it, which will normally split it wide open without much effort. Different species of wood have different characteristics though, so terms and conditions apply.
Just put it in a old small tire :)
Neither mine, I have a machine that does it for me. Much safer and efficient.
Remember: this is the worst that splitting firewood will ever be.