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.
Step 1: Use a Potentiometer and Buttons Instead of Sensors
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.
Step 2: Use LEDs Instead of Relays
Realys are big! Use leds to simulate then.
Most of the time, if you can control a led, you can control a relay.
Step 3: Have a Small Breadboard Always Ready
In light of what we said in the previous steps, we shall build a "ready to go breadboard".
I have tried to use the prototyping shield from Arduino, but I found it way to small.
I bought this breadboard and build the circuit showed in the photos. Notice that I got 2 potentiometers (x and y), 3 leds and 3 push buttons.
I keep this breadboard always like this and most of the time it suffices for prototyping and coding.
I always keep a few wires in hand as well.
With this breadboard I rarely need tools like pliers, screwdrivers, etc... Of course, as you prototype passes the coding phase you will need to build your boards, test your sensors, etc... But till then, My work got cleaner and more organized.