The title of a Service Design principle changes its whole meaning. Like a book cover that sets the tone for the book, it's important to take a minute to get this right.
Start your principle with a verb: by starting with a verb you get a sense of the action that you should take as a service creator.
Write as if it was a user advice: writing like this reminds us that we are doing all this to serve others.
Add something to make it memorable: for me a touch of street language does the trick to show the level of emotion.
Try out different titles: list several titles options and then choose the best one.