Testing is the Religion
Best Practice 5 - Testing to be followed like a religion.
Testing is mandatory after every small or big change, no matter how tight schedule you have or you just changed a small comment inside the code, you have testing due for the changed code.
There is nothing like trust while developing software, no matter how expert or how senior you are in writing source code, you would have to perform testing for each and every change you did in the code.
Tight schedule, no compromise.
Changed just a comment, still you have to test it.
Changed just a variable name, testing has to be done.
If you feel lazy...it's too dangerous.
If you don't want to follow it? You will be in trouble!
Celebrate every bug you find
Yes, you should not feel unhappy if you or another tester finds a bug in your software source code. Following are the enough reasons to celebrate this important discovery:
Bugs are your enemies, so you have killed one.
Now your software is having one bug less.
Mistakes are good as long as they are not repeating.
What you learn today, prepares you for tomorrow
Same time, do not criticize any developer in case any bug arises in his/her code because so far at least I do not know any programmer, who can write bug-free source code in the world, second this is one of the reasons we have a separate phase in SDLC (Software Development Life Cycle) which we call post production support (or support & maintenance).