True an erotic author must write accurate sex, it doesn't make sense to stick 4 dicks into one pussy at exactly the same moment for example, but developing realistic fantasy could almost make that believable.
The fantasy may be one of the reasons that erotic literature is supposed to be mostly for the female. Many women that I know wouldn't dream of watching raunchy porn and the idea of seeing blemish marks from the lash makes them wig out, but they enjoy reading about it, visualizing it within their mind's eye. I knew a woman who was in love with Jack Sparrow - not Johnny Depp mind you. Jack Sparrow, the character, the fantasy, and idea of him.
Erotica encourages these fantasies to be played out, nourished, fed, visualized. Whether a piece is intensely detailed or flashes of quick story, the better it is is directly related to the connection between the reader and the fantasy.
So play with your fantasy, allow yourself time to dream in bed, in the shower, on your lunch break, notice what your body reacts to. Notice what parts you spend the most time on, is it a fantastically detailed cock? Is it the thrusts in and out and in and out? Is it the moans escaping her soft pink lips? Is it the scent of sweat and sex? Is it the taste of salt from the work out you just finished? Develop the moments that most enchant you.