Testing Advice in Eleven Steps. My favorite:

At any given moment, the next test has some chance of costing you time in the short term. The problem is it’s nearly impossible to tell which tests will cost the time. Play the odds, write the test. Over the long haul, the chance that the tests are really the bottleneck are, in my experience, quite small.

All eleven are pretty handy for those like myself who still feel like they have a lot to learn about TDD, BDD, et. al.