Okay, back on track. This tip is going to seem obvious, but it's one I see a lot.
When you are writing a scene make sure your characters are acting the way real people would and not the way you "want" them to act.
Often, as writers, we create a scene in our heads and write it without giving it the reality test. Recently I was working with a writer who had a great scene where two girls wake up in a locked room with no memory of where they are or how they got there. Because the author knew what was really happening in her head, the girls were fairly calm, exploring the room, opening drawers looking at clothes, comparing notes, etc.
The problem is, that's not how real people would behave. If most people woke up locked in a strange room, they would freak out. They'd be yelling, pounding on the door, trying to break the window. Later, when they discovered what was going on, or when they realized they couldn't get out, they would take stock of the situation. But not at the beginning.
This problem is very common in almost all genres. In romance, your characters fight or smooch because you need them to, not because there are good reasons for it. In thrillers, your character goes into the haunted house because you have to have her attacked--when in reality she would be running at top speed away from that place.
Of course, you can have your characters go in the scary house, smooch, explore the locked room, or not. But you have to give them good reasons.
Also, be careful of the "that really happened" excuse. This is where you have something implausible happen by pointing out that it happened in real life. "I know it seems unlikely that the man and woman would randomly meet on the other side of the world on the very date of their original wedding, but it really happened."
Your job as an author is to create an illusion of reality. This means that it has to be believable to the reader. If it really happened, but it is incredibly unlikely, you have to create a better reason than coincidence or you will lose your readers' faith.