The ball of your foot should be over the pedal axle. The foot should naturally be at this position when you cram them in there, if you have the right size cages for your shoe size. The straps are meant to be tightened down every time. It takes a little practice to get used to flipping the pedal and inserting the toe, with the cranks spinning, without looking, and while looking cool. You only have to do it with one pedal though, put your other foot in while you're stopped.

Get a front brake and you can go fast!