If I had a penny for every time new writers made this mistake, I'd be richer than Amanda Hocking. You know what I'm talking about: punctuation. Specifically, punctuation involving quotation marks.
I don't know what it is, exactly, about quotation marks that makes perfectly capable writers suddenly punctuate like they're drunk texting. Here, I'll give you an example:
"I can't believe it." She said.
No! Bad! Rule #1: When using the tag "she said," or for that matter "he said," or "[name] said," use a comma (instead of a period) before the end quotation mark and use lowercase for the dialogue tag. That's because in this case, "she said" is just clarifying that she, in fact, said it. This gives us:
"I can't believe it," she said.
Rule #2: If a sentence ends with a comma or exclamation point, keep that and put the next part in lowercase:
"Do you really believe that?" he said.
"Yes!" she replied.
But wait! There's more. #3: When a sentence describing an action follows the quote, you don't need a comma or lowercase.
"That actually happened!" She started waving her hands in the air to prove her point.
"It totally did not." He said this while looking at the floor.
So, to recoup: comma (or original punctuation for anything but a period) and no caps for just "she said" (or "she rambled" or "she monologued" or anything like that), but continue normally for a regular sentence. This sounds logical but I see new writers flummoxed by this a lot.