I'd like to preface this with a disclaimer: In writing, there are no rules. None. If anyone tells you never to do this, or you should always be doing that, they are wrong. There is always a bit of fuzz, a bit of 'but what if-', a smidgen of flexibility. But most of these 'rules' have good intentions. They have reasons behind them, and before breaking them you should consider those reasons.
With that said, let's begin.