Tip 8: Keep learning!
Just like learning new programming languages makes you a better developer, learning about new testing approaches, libraries, and tools will make you a better tester. The state of the art of testing is changing very rapidly these days - new frameworks and techniques are released almost every month. Keep looking at example code and trying out new stuff.
For instance, here's a few tools that you may not be using but are very cool: Heckle and RushCheck
Finally, if you want to learn more, subscribe to Jay Field's blog - he has lots of good (if sometimes controversial) thoughts about testing.
And with that, I'll wrap up this series on testing. If you have your own testing tips, please share them!
