What I look for in a software tester is someone who breaks the code. When a programmer is unit testing his code, he is tryi9ng to proved it works. When I QA person is testing code, they need to prove the can break it. How? Do things that are illogical and see if you get restrictions or errors. Develop a good base testing plan so that you can do regression testing easily. More errors are introduced when a “problem” is fixed.