It took me a long time to learn this but there's a compassionate way to be honest
  1. Make sure to point out the positive things first
    Sometimes they are hard to find, honestly, but still find them
  2. Make sure to establish that you are there to support the person who made the thing and to help them and you are in it together
    Even if you're in a rush, even if you need to send the thing/publish the thing stat, say things like "don't worry!" "You totally have this!" "I think we can make this even more amazing"
  3. Use question marks at the end of sentences that should not have question marks
    this makes your edits sound like suggestions instead of demands (even if they are actually demands) "I'm not sure if people will care about XXX?" "The point of view seems off?" "I feel like we need a stronger close?" "Tighten up this section?"
  4. Blame it on yourself
    Especially for the parts you just know the person worked really hard on/loves "This is probably just me but..." The person will probably know it's NOT just you but it's still nicer
  5. Never use all caps
    This might seem obvious, but when I started out writing all of my mag editors used all caps which of course felt like someone screaming THIS IS CRAP AND YOU ARE SUCKY
  6. If you are an editor let the writer have one or two things that you don't love but that are meaningful to them and ultimately don't affect the quality of the piece
    Another way to say this is: choose your battles
  7. Remember that you are speaking/writing to another human with feelings, that your ego doesn't win anything by being "right," and that you both have the same goal to make the thing the best it can be
  8. Take deep breaths and breaks often
    especially if the thing you are giving feedback on is actually terrible
  9. Holy shit American Pie is long
    Suggested by @fats