Okay, I just finished reviewing a number of entries or a writing contest. A lack of self-editing set the entries apart, and many of the entries had the same common mistakes. What were those mistakes that cost entrants valuable points?
1. Prologues filled with back story: By its very nature, a prologue is back story.
However, a well-written prologue moves that back story forward. Authors should never make the mistake of beginning a prologue only to include information that preceded the time of the prologue.
2. Starting the story in the wrong place: How can an author determine if he's started his novel at the wrong point in time? One indication is the need to fall back immediately into back story. If the back story is so important, this might be where the story should begin. Another indication is blocks of narrative providing the reader with an explanation of where she is at this point of the story. A good practice is to always start your story in media res. In short, drop your characters into the action and move forward.
3. Telling rather than showing: In most instances, this is even done by more experienced authors. It's a tendency to drop in telling phrases such as she heard, he knew, she realized, he saw. In most instances these phrases should be avoided, and they are easily removed by taking off the phrase and changing the tense. This brings the reader one step closer to the action. Another form of telling is more evident. Large blocks of meandering narrative that tell us everything the character has done, will do, and plans to do before it occurs. Most times, this information isn't even necessary. Often, if it is necessary, it can be delivered in smaller bites throughout the manuscript and not dumped all at once for the reader to chew on and grasp.
4. Punctuation: It's a small matter, but mistakes add up. One or two errors can be chalked off as typographical. More than one or two, and the judge, editor, or agent sees very clearly that the author has lack of understanding. Oh, and one important mistake that dates an author is the use of double spaces after end-of-sentence punctuation. Always check your document for those spaces. The rule is a well-known one, and to discard it, marks the author as either a rebel or someone who has not worked hard to know their craft.
5. Spelling: Again, it's the little things that drive the judges, editors, and agents crazy. If you're writing about a certain locale--a famous locale--one that is on every map in the country--spell it correctly. If a red squiggly line forms beneath a word in your manuscript, look it up in the dictionary, because there's a better than average chance the spelling is wrong.
6. Grammar: An author doesn't have to know the definition of a dangling participle or the names for each part of a sentence. An author should know what makes the continual use of an adverb in a dialogue tag the wrong course of action in most cases. There are certain rules that, when broken, will mark an author as a newbie. Knowing the basics is a plus.
And there you have it. These common errors do make a difference to judges, to editors, and to agents. When entering a contest, it is always best to review the score sheet. Most are provided for the entrants, and they are a good way to ensure your entry makes a better than average showing in any contest.