The longer I've been writing, the more I get annoyed by writers who tend to spout off "rules" as though they are the absolute end-all, be-all for a writer to be effective.
Write Every Day!
Well, if writing every day works for you, then sure. Go for it. Write every day. But some of us aren't effective if we write every day. Some of us have three days a week set aside for writing. Some of us write every day for spurts of time, and then need a week or a month off in order to recharge, and then do it all over again. (I'm in another recharge phase right now.) Use whatever method works for you.
Use Short Sentences!
Some people have a voice and a writing style that is conducive to short sentences. Others do not. Hemingway was a master at writing with short sentences. Faulkner was a master at writing effusive sentences. Both were successful. Don't worry about the length of your sentences, as long as they suit your voice and aren't actually unintentional run-ons or fragments. If the sentence is technically a complete sentence, and if your meaning is clear, then there isn't a problem. I, for one, love nothing better than a beautifully written, well crafted long sentence. Write what works for you.
Avoid Adverbs and Adjectives!
Maybe this one should be "limit" adverbs and adjectives. Excessive use of those pesky parts of speech can be a sign of weak writing. But completely (heh! I used an adverb!) eliminating them from your writing can make for some boring prose. They are in the English language for a reason after all. Learn what works for you, and stick with it.
Avoid "To Be" Verbs and -ing Verbs!
Again, overuse of "to be" verbs can be a sign of weak writing, particularly when they are utilized in a way that makes your sentence passive. But sometimes, a writer can work so hard to avoid using that pesky "was" that they create a clumsy, clunky sentence that isn't as effective at getting their point across. By the same token, those -ing verbs have gotten such a bad rap that a lot of writers will go through, pouncing on them all and eliminating them from their writing, when actually they should have left them alone. By changing them, you just might be changing the tense of your verb, and saying something that you don't mean to say. So learn the rules--learn what makes a sentence passive, and learn about verb tenses--and then it will be easy to figure out when you really should cut out the "to be" verb or eliminate an -ing verb tense.
It is so easy to get caught up in all the rules, to become so focused on doing everything the "right" way (whatever that is), that we lose our voice or lose our story in the process. There is no "One Size Fits All" rule for writing. That's not to say that we shouldn't learn why these supposed rules have been put into place. But don't get lost in trying to follow them.
What other "rules" are you ready to toss out the window?