Well, writing about sex. Or more concisely, writing sex scenes:

The best sex scenes are the ones that deepen and reveal the characters or forward the plot.  What’s the key to writing good sex scenes?  It’s the same standard as any scenes in fiction:  Story logic (don’t ram them in, so to speak), emotional honesty and attention to detail.  I also try to walk a line between being too clinical and too coarse.

I wonder if the genre and writer makes a difference. The collection that I’m working on comprises quite a bit of sexualities and frank scenes of getting down and dirty. Does the above sage advice hold true for all types of writers?