What Textured Ideas says basically covers the most common problems. There are a couple of other common problems I've noticed:
- " '....I like that idea, too.' She said." (" '....I like that idea, too,' she said.")
- Double-spaces or even triple spaces after period. ("..., she said. The next day...")
- Question-mark in the wrong place: "Why is that, he asked?"
- No spaces after punctuation: "...better late than never.The next day..."