I always introduced myself by name and that broke the ice. Remember, it's mostly the same familiar faces at these milongas. An unknown sitting in the corner is hesitantly cabeceoed.
Introductions by
name are important even among mostly familiar
faces at local events! I've seen the same followers around for years in some cases, but they've ignored my invitations until we've chatted off the floor and learned a little about one another, beginning with names. The ice broken, we then dance when we cross paths at local events.
An extension of this is the courtesy of introducing your regular life/dance partner to people known to you but not them. For instance, I used to work at a studio where I tended bar and accompanied many dozens of followers without partners, so I met a lot of people – men and women, leaders and followers. Since then, I've gone out to dance more than my partner, whose medical situation means she has less energy than me. So, when we show up to a milonga together, I know far more people than her . . . and when we cross them at the entrance, in the cloakroom, at the bar, or on the edges of the floor, I make an introduction. My partner dances a
lot more because of that.
I realize that some people prefer "anonymous tango," where then silently invite, dance, and disappear, and don't converse or make acquaintances. Some enjoy the anonymity of a whole other city or country. They're seeking to dance – not to join a community. Still, if you frequent a local scene for years, intros by name for you
and those you are with are a big deal; I'd say essential.
Remembering names is a separate issue.

I'm fortunate to have been the coordinator of large university courses for years. My father, a career lecturer and educator, taught me the tricks to remember the names of 400+ people in a group. But here in tango, 90% of the followers I meet are named Anne, France, Geneviève, Lyne, Sophie, Stéphanie, or Sylvie, which makes life tough . . . stand-out names (especially non-québécois ones like Angelina and Salomé) are easier to remember.