I 'll be using is a simple spring/nail type sensor..
and a ballbearing (tilt/swing) type sensor
Both of those produce a lot of contact bounce. First off try a 10K pull up resistor and a 0.1uF capacitor across the input. Arrange your switch so that it connects the input to ground. After the first pull down it will take some time for the capacitor to charge and put a logic one back on the input. The idea is that the second contact of the bounce discharges the capacitor before it reaches the level where it looks like a logic one. It is only on release that the switch that the capacitor has time to charge up to a logic one level.