It all begins with the purpose of your memo. Think about what you want to achieve with it. Simply said: the easier the answer, the more specific your request.

Don’t let yourself get carried away with too many details and the pro and con of it when you write it. Keep the message concise and clear. 

Post-it stickers are of course emotional. But other than for these better refrain from becoming emotional, simply because it affects straight forward results. Make sure that everyone understands what you expect. And this automatically means as well: choose your group of recipients wisely. Better write two memos, if your expectations differ when it comes to certain people within the group.