When being critical is unavoidable start your sentence with “I feel” statements, instead of “you” ones.  

For example, “You are always so grumpy when you don’t get your way” could be turned into “I feel like you are mad at me because we didn’t go out last night”? 

Do you hear how harsh the first statement sounds?  It is next to impossible to say it without coming off as mean even with good tone, where the second statement is simply how you feel at the time, sounds more subjective, and is critically neutral.  

I know this may sound like a little thing, but to me this little change in phrasing is one of the keys to sustaining great friendships, a great marriage, and a great relationship with your co-workers.  

Can you imagine (ever) fighting with your spouse (again) if this was how you agreed to speak to one another for the rest of your lives?