On-the-Nose Dialogue - On-the-nose dialogue that tells the reader exactly what you want him or her to read. No mystery or intrigue, but just saying it all outright in "on-the-nose" statements are hallmarks of weak writing.
Story Exposition in the Dialogue - Telling your story through dialogue in long monologues. Please tell the story in the narrative unless it's a narrator.
Repetitive use of characters' names - How often do you actually say someone's name? Not often, so please avoid the same in your writing.
One voice, many characters - All of your characters sound like a middle-aged white guy. Make sure you have unique voices for each character. Tip: use a real person you know or actor or actress and base your character on his or her voice. Study how the person talks, expressions, tone and inflection.
On-the-head storytelling - Not to be confused with "on-the-nose", because this is storytelling where you don't respect your reader's intelligence and hit them over the head with your story, themes or metaphors. You literally "tell" them and in doing so you don't allow them to think for themselves. Telling them what to think loses intrigue, mystery and interest.
Impatient writer's syndrome - I made this one up, but it's a problem where the writer rushes to tell the story and doesn't develop a real story or characters. The impatient writer doesn't take his or her time to develop, describe and create a fully realized world populated with interesting characters.
Flowery, cluttered writing - Over description of minutia and settings will kill the pace of the story. Unless the minutia is an integral part of the story, don't describe it. Modern writing steers clear of flowery language, so avoid it. Make your story move and flow and grab your readers.
Just too far out - Readers can only suspend their disbelief so far before they just give up on your story. Your world has to have rules even if it's a fantasy world. Your world has to make sense to modern thinking. It has to fall within the constructs of an actual world where logic still applies. Creating characters or worlds so far removed from the typical reader's ideas of reality will cause rejection. For example, most people don't suck blood to eat and live forever, but we all understand the need to eat and desire to live; therefore, we can relate on some level to the idea of the vampire. A genderless blob with no personality that does nothing but float and do nothing isn't particularly relatable to anyone. We are all searching for something that is emotionally resonate and makes sense to us. Make sure your story makes sense.
Wrong Structure - We all have expectations about how a story is told. You can't hook a reader by telling the end at the beginning. You can use a "hook" to reveal something about that end to keep the reader engaged, but you have to them tell the story that actually reaches the end. Writers who so disrupt the natural, organic storytelling experience had better do so with skills and brilliance otherwise they will lose their opportunity with the audience and be rejected.