Epictetus was very keen on action - on demonstrating that his students were actually living the philosophy they were learning. This is another passage where he emphasizes action over rhetoric.
"Tell yourself first of all what kind of person you want to be, and then act accordingly in all that you do" (v. 1, p. 193). If you start with the end goal in mind, you will know when you have accomplished it or when you are making progress.
"For in all that we do, unless we refer our actions to some end, we'll be acting at random; and if we don't refer them to an appropriate end, we'll go badly wrong" (v. 3, p. 193). If you don't have a heading, then you'll be heading toward a random point. You must be clear about what your goal is.
He further clarifies to those who would want to teach others where to head (philosophically speaking). If you "want to be of benefit to others" you must first bring benefit to yourself. In other words, in order to be able to teach, you must be able to demonstrate your mastery of the topic.
More specifically about Stoicism, he explains what those milestones in progress are. "Has he acquired self-restraint? Has he look in on himself? Has he become aware of the bad state that he is in? Has he renounced conceit?" (v. 16, p. 195).
Then there is this interesting passage which reminded me of what many people do in this era of social media. He says, "While you're in such a wretched state as this, then, and have such a hankering for praise, is it by counting the number of people in your audience that you wish to do good to others?" (v. 19, p. 195). The admonition strikes near those who pursue the greatest number of Twitter followers or "likes" they get on social media platforms. The purpose of all teaching is to actually help other people, not to be popular.
The real evidence of being able to have an impact on other peoples' lives is if people naturally follow and listen. A philosopher does not invite people to come and listen to him, but rather it's "just as the sun draws its nourishment to itself without need for further action, a philosopher likewise draws those whom he can benefit" (v. 27, p. 196). He also notes that a doctor does not invite people to come to him to be cured, rather people seek him out to be cured.
"A philosopher's school is a doctor's surgery. You shouldn't leave after having had an enjoyable time, but after having been subjected to pain" (v. 30, p. 197).