The "I can't cook" thread got me thinking about where most people go wrong when cooking, and I am forced to agree with my splendid husband, Jackp, on this topic: it is attention to detail that screws 'em up every time.
You can have the best piece of steak in the world but if you don't pay attention to it while you're grilling it, you're going to end up with steak jerky. And not very good steak jerky, either, since it probably doesn't have much seasoning on it.
You can start out making brownies and over-blend the ingredients and destroy the leavening.
You can be cooking pasta - the simplest thing in the world - but start watching television and the next thing you know, you have a pot full of starchy water with some floury worms floating around in it.
Whether it's timing, seasoning or the ingredients themselves, it's that attention to detail that makes or breaks the dish.