The inclination is natural, I suppose: we go to school to learn just about anything else, so why shouldn't there be a class or book or seminar that will teach you how to be a better smut writer?
Without getting too heady, the idea that there's a special—perhaps secret—way of getting you from bad to good, or unpublished to published, or unpaid to paid, is a bit disturbing. Ruminating a bit too much on it can make it all a bit like a paranoid fantasy, like there's a trick or a jealously guarded connection that allows other people to make it and keeps you out. But take my class, buy my book, attend my seminar and you too can learn the secret to successful erotica writing ... just don't tell anyone.
Without gnawing off the hand that feeds me, I feel guilty teaching writing classes. Standing in front of a room full ... well, a few dozen, tops ... of green writers, all of them eagerly waiting for the secret makes me want to confess it all for a sham, and in so doing spill my guts on the real true way to become a better writer, of erotica or anything else.
Not that a class or two can't help, especially any classes that highlight some of the less-than-fun elements of a writer's life. If you're lucky, you might find the right kind of class, book, or seminar that gives—quickly and honestly—the sad facts of finding a market, writing a cover letter, formatting a story, dealing with publishers and editors, and so forth. Those kinds of books and classes can definitely help with the paperwork side of writing, especially since screwing any of it up can stop your story from even being read, much less considered. But they can't make you a better writer.
The worst of these kinds of classes and books are what I call Frog Killers. You've probably heard the analogy before: you can study how a frog is put together by taking it apart, but you can't put it together again afterwards. A book or class that focuses on picking apart a story—usually to a ridiculous set of specifications and standards—usually does nothing for new writers but make them hideously self-conscious. They write but then freeze up, panicking that they've forgotten the character transformation, that the story isn't emotionally engaging, that there's no conflict (man vs. man, man vs. nature, and whatever that other one is), that there's no clear A-B-C structure, and so forth. With this oppressive laundry list in their heads, yelling at them louder than their nascent creativity, no wonder budding writers can feel like deer caught in headlights. This is why, when someone's resume indicates that they have a degree in creative writing, I look at them like they'd stormed a hill under heavy enemy fire. It doesn't make them better writers, though, even though they might be able to tell you—to ten decimal places—why their story is worth publishing.
The other kind of book and class you might stumble across in your search for guidance is the philosophical one. To be honest, I like these much more than the Frog Killers—more than partially because it mirrors my own idea that writing is more magic than science. These kinds of teachers approach writing as art, usually with a series of literary touchy feely exercises that will stretch and tone your currently saggy imagination. The only problem with these is that they can all too often retreat from the idea of writing as being work, taking away the 90% perspiration in exchange for the 10% inspiration. Creativity is one thing, but you still have to get the damned thing down on paper.
As far as I know, the only way to be a better writer is ... drum roll, please ... to write. Not much of a surprise, is it? Some classes and books might be good for the basics, and for the nuts and bolts of the business. Forums might be fun; newsgroups might be a diversion, but the only thing that will make you a better writer is to do it, and not stop doing it.
It's a nasty rule, but aside from a few very rare exceptions, your first story will suck. It will suck painfully, forcefully, and with great vigor. So will your next one, and your next one, but eventually you'll get better: your language will begin to flow, and you won't be thinking about writing but will instead be telling a story. After that, you'll find yourself enjoying the process, nodding at little turns of phrase or a well-toned paragraph. Later you'll feel tears on your cheeks when you put THE END on something that worked out perfectly, beautifully.
Do you get where I'm going? No one can really teach you that, just like a paint-by-numbers kit won't turn you into Picasso. The only way you can really get better as a writer is to try and fail, try and fail, try and fail, try and fail, try and fail, try and fail, try and fail, try and get a bit better, try and get a bit better, try and do something good, try and good something better, try and make something great ....
So what are you reading this for? Get back to writing.