Well, my foolproof method is somewhat a party-trick of sorts. It involves propelling the egg out of its shell...
First, you crack the egg at the top and the bottom, and on both sides you gently peel a circle of shell off the egg with a diameter of about 1cm. On the bottom this is easy, on the top... be gentle...
After this is done, put the egg in your closed hand with the exposed top to your mouth and blow hard (make sure you keep hold of the egg).
The video below explains it in visuals, though the bottom hole is a lot bigger:
