1.Passive voice.
This is the single most common error. More people make this mistake, and make it more often, than any other error in the writing of fiction. Let me rephrase that sentence, so as to illustrate the problem: This is the mistake most commonly made in all fiction. Note that in my second rendition, no one makes the mistake. It is simply "made." It is not clear that it is a mistake in writing. You could interpret the second rendition to mean that readers make the mistake. In passive voice, nothing is ever anyone's fault, because people do not do things. Things happen to people. "Irving ate the food" is active. "The food was eaten" is passive. Note that Irving has vanished completely. The food and the action of eating are made more important than the person who does them.

2.Inappropriate use of summary narration.
This is closely related to passive voice -- the two errors frequently overlap each other. Summary, or indirect narrative is the flip side of the coin from direct narration. You sum up events, tell about them, rather than show them. As anyone who has ever stayed awake in a writing class knows, you should strive to show as much as possible, and tell as little.

3. Time Control Errors.
The most common variant of this is the needless flashback. I have seen stories that started with a flashback, then jumped forwards in time 30 seconds. What's the point? I am convinced that a great many flashbacks happen because the writer has read lots of books with a flashback and felt the need to conform to a literary convention. Yes, flashbacks can be cool, and dramatic, and exciting. But bear in mind that part of the reason they induce a sense of drama is that they cause confusion and uncertainty. They are intended to make the reader wonder "What the hell is going on?" and read further. But drama based on bafflement and doubt is a tricky thing. Far too often, flashbacks merely make the reader wonder "What the hell?" and give up in befuddlement. Straight flashbacks are only the start of it, of course.

4. Unnamed characters.
Of all the errors, this one puzzles me most. I cannot understand why people commit it so often. I suppose that it is out of a desire to induce a sense of drama, but it rarely works.
The classic example would be a twenty-page story, wherein we follow around a nameless protagonist for 15 of those pages. At long last, it is revealed, with high drama, that her name is --"Jane." Wow. Or it could be any other name to which neither real life nor the story has attached any special significance. There is nothing surprising in a person's name. Everyone has a name. Revealing that your lead character has one too, and even revealing what that name is, will not likely shock anyone. The ONLY reason to avoid revealing a character's name is if you are doing one of those tired old things where there is a misfit little Austrian boy nearly hit by a horsecart. His life is saved by a kindly Jew and we find out the kid's name is --(what a shock!) Adolf.

http://www.authorhouse.com/GetPublished/FAQ.aspx

Don't get "inspired" by other works of fiction. Far too often do I see things in books that are ripoffs of other's ideas. I swear I have read 15 different versions of StarWars...

You get my point, just because something is a popular concept does not mean you have to use it. Swords of light and drives of warp are not something that should show up in other peoples books. That could go for any fiction, not just sifi.

Elation did find a decent loophole in my concept, truely the unnamed characters concept is stricly depending on the writer. Although its not recommended todo because most people do it horribly, I have read the Time Machine and I will agree that it does put the unnamed concept to shame.
So I would have to say it depends on the writer.

5. Actions
Your character wants to get home and sleep in his own bed. You, the writer, want him to be there when all hell breaks loose. You have a good plot a reason for sending him to the edge of the volcano's crater. But does he have reason? Your plot may require your heroine to fall in love with the sleazy thug -- but doesn't she have more sense than that? Is it in character for her to find such a scuz-bucket attractive? Or think of it another way. You are a lab scientist who puts rats in a maze. You plan to kill them and dissect them to see how learning changes their brain chemistry. This is not the rat's reason for going through the maze. The poor little bastard is just looking for a piece of cheese. Both writer and character must have a motivation for each action in the book. Much or most of the time, their motivations will not coincide.

6. Failure to deal with consequences.
As an example, say your setting is in a post apocalyptic world where the government ceased to exist, and somehow you have a character using paper money. That wouldn't happen, seeing as how there is no government to back up that paper's value. Failing to deal with consequences has to do with more than technology. If you write a story about someone who grew up in an orphanage, and that person goes to a big family dinner at a friend's house, the orphan's background will affect his reactions to a roomful of grandparents. It will seem damned odd if he doesn't have some massive emotional response to the family relationship that been denied him. It can something subtle, like a city person using language and imagery that only make sense if you are from a rural area. Of course, science fiction and fantasy are especially prone to this law of unintended consequences. Some other examples, which have, sadly, seen print: knights in armor climbing aboard a starship. A high-tech civilization based on machines operated by uneducated slave labor. A world of cybernetic connection where anyone can assume any guise or appearance at any time -- and yet people are discriminated against for being what no can know they are. If you write a story where they finally do shoot all the lawyers, who'll try the cases when the guilty are brought to justice? Don't just ask yourself what if once. After you get your answer, ask yourself what if about the answer, and then ask it about the answer to your answer.

7. Bad Planning.
This happens, in part, because inspiration is overrated. We have all seen the plays and the movies, read the books, where the lightbulb goes off over the writer's head and he or she suddenly starts cranking out brilliant copy non-stop. This is nonsense. It takes a seasoned write something like six months to a year to write a book. If they had to be that inspired in order to write, they would have had a heart attack by now. The wise writer takes notes, jots things down, makes a mental note, mutters into a bedside tape recorder those things that seem inspired at two a.m. and are merely incoherent in the morning. Those jottings and mutterings and scribbles are inspiration preserved.

8. Failed Exposition.
This typically -- but not always -- happens at the beginning of a story. Instead of getting action, or the story, we get background, told from no particular point of view. Sort of an encyclopedia entry on the subject in question. For some reason, fantasies are particularly prone to this flaw. The story will open with a long explanation of how the castle (or fortress, or bus station) came to be there, and who all the ancestors of the current duke (or king, or wizard, or head chef) were, and how the magic (jewel or ring, or crown, or polo mallet) came to be imbued with its powers and then stolen (or lost, or locked in a spell, or pawned). We then spend the rest of the book in search of the map (or book of spells, or claim ticket). Most of what goes into such expository lumps is pretty generic. All castles were built, all rulers had some sort of ancestors or predecessors, all macgufffins (that being Alfred Hitchcock's term for the magic jewel or secret formula or other gimmick around which the plot revolves) are important, and if they weren't out of the hero's possession, there would be no story. Much of such material can be assumed, or else you can work it into the story here and there, rather than spewing it all out at once.

Akiyo:

1.Passive voice.

Okay, I think I understand that one. Luckely, I don't think I've made that mistake yet, or if I have, I'll probably end up editing it out later on a re-read since it doesn't have a subject.

2.Inappropriate use of summary narration.

Yeah, I read this somewhere in one of Deadron's posts. When things get explained instead of shown. "Sometimes less dialogue is better."

3. Time Control Errors.

Yeah, i've read a few novels like that and didn't like how the way the time was laid out because it left me going "wtf??" when it was over and was starting on normal time.

Thankfully the books I listed are pretty short. Not epics, so uh, get to 'em! :p

If you're asking for or about multiple things, use "are" instead of "is". :/

*Edit*

Pet Semitary isn't exactly an ideal model for good writing.

Pet Semitary isn't exactly an ideal model for good writing.

I know some of the bad things about it, but could you tell me your observations?

Great tips there, Akiyo, although I do take issue with one of the points in #6. Armored knights climibing aboard a starship makes for darn good reading, as witnessed in Poul Anderson's The High Crusade, doubtless the misunderstood inspiration for that lament. It worked in the story because the author found a way to work out #5: The characters' motivations coincided with the author's designs.