What we call the beginning is often the end. And to make an end is to make a beginning. The end is where we start from.
Congratulations! You've reached the end of this book. Either that, or you're the kind of person who likes to spoil an ending by reading the last page first. (If you are: The butler did it.) Presuming that you've read every chapter, by now you should have:
Learned many practical code-writing techniques that have already improved your source code.
Gained an understanding of how to write code in the Real World and the tricks that help you to produce useful code in the madness of the software factory.
Worked out some personal ways to improve your skill set. (You did attempt ...