I will admit, I feel very nervous, very hesitant when it comes to instructing in piety. I am willing to do a very simple baseline - be respectful, things like that. Or I will explain things that I do from my piety - I have no problem teaching why I make the sign of the cross when I do. And, if someone is assisting me in the service they will reverence when I want them to.
But I am not likely to write a handbook on "this is how you should do things" -- because of a very simple reason.
I view the distinction between piety and pietism as this:
Piety are those things that one does in order to focus ones self upon Christ and His promises. One should be able to articulate the why of these (as an adult).
Pietism occurs when one says that others *must* do one's own piety. Why does not come into play (either why they must or even why I do something).
I'm not going to tell someone that they must kneel during the Confession, even though I do. I like the humble posture - it reminds me that of myself I dare not stand before God almighty. But I'm not going to say, "If you don't kneel... bad!"
And of course, this applies to things outside of worship. I may choose, out of a desire to exercise self-control and discipline, to forgo X... but I can't tell another, "You need to give up X." I can explain, or even suggest if they ask -- but to command - no.
I cannot assume that I know better how to face the trials you face in your life than you do. I can warn of sin - I can suggest... but to say "Thou shall" when our Lord has not said "Thou Shall" terrifies me. It is too audacious for me. Piety suggestions must always be that - suggestions.
Because ultimately... while piety is good, the specific shape of piety doesn't matter... the size and shape of the sign isn't nearly that important, as long as the sign points to Christ.