As a busy but unpublished writer, I feel uniquely qualified to dispense advice and rules about writing. Everyone else is doing it, so why can't I?
It should be said that any rule of writing can (and probably should) be broken at some point. My take is that, as we're learning new skills, we need the fundamentals before we begin vamping on those fundamentals. (A pitcher needs to know how to throw a baseball before s/he can throw a curve ball; am I right?)
That said, here is my first Rule For Writing:
Thou Shalt Not Create a Character Who is a Writer
What could possibly be wrong with having one of the characters--or even your main character--in a work of fiction be a writer?
Let's start with the fact that writers are inherently uninteresting people. Writers are folks who are, on their best days, neurotic, compulsive and narcissistic. They are preoccupied with extracting aspects and details of their impoverished inner lives from their enfeebled imaginations and wrestling those fantasies onto the page in some aesthetically pleasing fashion. Writers don't do much more than emote in front of a typewriter, computer, pad of paper or whatever. The only dramatic angle is whether or not the writer is feeling positive about the state of his or her work (he or she isn't). And who wants to read about that?
I don't. And you don't either.
Then there is the very lame Rom-Com-esque conceit of conferring upon a character the preoccupation of writing in order to convey that this person is somehow intrinsically sensitive or insightful or romantic. Bah, I say. BAH. In these ridiculous scenarios, the writer is inevitably pitted against some 'bad boy' type who dresses in leather, rides a motorcycle, is sexy as hell, and yet, lacks the soulfullness of the writer character.
Bullshit. The 'bad boy' is the far more interesting character. The 'bad boy' is about something. The 'bad boy' has a mystery. A mystery that the reader wants to discover. The writer? There is no mystery there. There is no intrinsic drama (save for some pathetic bitching about how the world can't possibly understand them). No one cares about the problems that plague writers. No one.
Just avoid this issue. Don't make any character you create a writer. You should probably stay away from artists in general, unless you have a unique angle. College professors are also off limits. (Unless you're Philip Roth.) The only people who think writers, artists or college professors make interesting characters are other writers, artists and college professors who make up .00013455 of the population and are, largely, insufferable boobs.
Try harder. Expand your imagination. Pick characters and occupations and pre-occupations that challenge you. Your fiction will be better for it.