Nothing recruits like visible joy. People want in on teams that clearly love what they do.

Nobody is persuaded into a group by an argument about its value. They are drawn by watching people who are visibly glad to be there, because that is evidence no poster can fake. Enjoyment is also fragile in a way that shows: a group performing enthusiasm looks nothing like one that is actually having a good time.

Rather than advertising your group, make the next session genuinely enjoyable for the people already in it. Protect the parts everyone likes even when they are not the productive parts. Let outsiders see it in progress rather than in a recruitment pitch.