After you know the basics of software testing, the question is how to master the craft. You should learn from the masters of software testing by reading their software testing work. This post guides you where to found such traces of software testing work. The post is based on a remarkable book written by Chad Fowler, The Passionate Programmer.
In software development, you master programming language by reading excellent open-source code. Github or Bitbucket are an excellent resource for that. But where to find something like that for software testing?
Lessons Learned In Software Testing is a book written by Cem Kaner, James Bach, and Bret Pettichord
The world’s leading software testing experts lend you their wisdom and years of experience to help you avoid the most common mistakes in testing software. Each lesson is an assertion related to software testing, followed by an explanation or example that shows you the how, when, and why of the testing lesson [Amazon].
These are resources that would get you started to find further examples of excellent software testing work.