There's a copy of the detail on this on the school system. It may be on the Learning Platform as well, I don't remember (e2a: yes, it's in the Newsletter production folder that you'll find in the AS Unit 1 section).
But here's the base list if the 12 most common newsletter design mistakes:
- Nameplate clutter - too much info in the newsletter name
- Lack of white space
- Unnecessary graphic accents - borders, lines etc...
- Text wraps
- Overuse of upper case type
- Underlining - just don't
- Long subheads - short and sweet, like me
- Inappropriate typeface choices - use serif fonts already
- Inappropriate type sizes - 12 is often too large for body copy you know!
- Insufficient line spacing - always think about increasing it a little
- Failure to hyphenate - arguments both ways on this, but it might well be a good idea
- Excessive colour - 2 colours plus B&W is recommended