There will come a moment in your experimentation when nothing will be working and you will have to figure out how to fix it. Troubleshooting and debugging are ancient arts in which there are a few simple rules, but most of the results are obtained through a lot of work.
The more you work with electronics and Arduino, the more you will learn and gain experience, which will ultimately make the process less painful. Don’t be discouraged by the problems that you will find—it’s all easier than it seems at the beginning.
As every Arduino-based project is made both of hardware and software, there will be more than one place to look if something goes wrong. While looking for a bug, you should operate along three lines: