The first rule is, let it happen, you spun, so you're dead, right? Fighting it makes it worse.
Centre the controls, clean up the plane (flaps, gear, whatever) can chop throttle.
Establish direction of rotation (look out the window), then, using rudder, steer into it the way you do a skidding car. As soon as you've stopped the rotation, you have to build speed. After all, a spin is a one wing stall, you're pulling to hard for your airspeed, that's why it happened. get fast, 200 mph in a jug, _then_ pull out. It's too easy to catch the spin, then while you're still at "mush" airspeed, to try to manouvre and do it all again. Keep the nose down and get the speed up first.