When many of us were in school, outlining had a lot to do with Roman numerals, Arabic numerals, capital letters, and lower-clase letters. As a result, when someone mentions outlines, we run away fast.
Outlining can be much easier than that. When you're planning a piece of writing, just jot down--in any order--the ideas you want to include. Then take a minute, or less, to put them in the best order for your reader.
If your ideas are on a computer screen, just drag them around. If they're on scratch paper, just number them:
"Let's see, I'll put this in paragraph 2, this in paragraph 4, this I'll leave out, this in paragraph 1, this also in paragraph 2, and this and this I'll also leave out."
Bingo. You have an outline. And you'll have a more effective message.