In this Istructables I'm gonna to give you a few tips about prototyping using Arduino.
I have used a prototyping shield to build my projects, and I've realized that most of the times that's not the best option.
Using a sensor must be a task apart from build your "main code".
Most of the sensor works almost the same way: it's a voltage signal, or a digital signal.
When you are writing your program, avoid using sensors to do it. Instead use push buttons and potentiometers to simulate the sensor.
This way, if you find a bug in your code, you know the problem is really in the code and not in the sensor.
Other good thing about it is that you can exactly control the "sensor value". Like, many times I had to turn on a cooler next to the temperature sensor to make the temperature go down and see how my program would react to it. Using a potentiometer can do that only by changing its resistance value.
You can worry about the sensor later.