This precept is "Set a Good Example".
How many times have you decided to do something because your "friends were doing it"? Or even have you ever convinced a friend to do something that wasn't really right because you were doing it?
I know I have done lots of things that hurt people, or made them feel it was okay to act like me, when it really wasn't. I don't even know how much grief has been caused by my not setting a good example, and I'm not a super influential person - like a president or anything - but even when you don't think you count to anyone, there's always someone who looks up to you. That's why I think this is a very important precept.
Take a look around you. Who might look up to you? Who should you set a good example for? Even if it's only for yourself, try setting a good example some time. Find out if it makes you feel better or worse. I'm pretty sure you'll find that you like the results.
Check out the Way to Happiness website for more precepts and for info on what Mr. Hubbard has to say about them.